Siento que no debería haber hablado tan rápido en la entrevista.

The verb sentir is tricky because it has several common uses:

1. Siento que…
   Here, siento means “I feel” or “I regret”, depending on context.

   • In this sentence, it’s closer to: “I feel (that) I shouldn’t have spoken so fast…”
   • It also naturally carries a sense of regret, almost like “I’m sorry that…”

2. Lo siento
   This is a fixed expression meaning “I’m sorry” (an apology).

   • You wouldn’t say: ❌ Lo siento que no debería haber hablado…

3. Me siento
   With me, sentir usually means “to feel (a certain way physically/emotionally)”:

   • Me siento mal. – I feel bad.
   • Me siento nervioso. – I feel nervous.

So:

• Siento que no debería haber hablado… = I feel / I regret that I shouldn’t have spoken…
• It’s not the same structure as lo siento, and me siento would change the meaning to “I feel (physically/emotionally) that I shouldn’t have spoken…”, which sounds odd in Spanish.

Both are possible, but they’re slightly different constructions:

1. With “que” + clause (as in the original sentence)

   • Siento que no debería haber hablado tan rápido…
     Here, que introduces a full clause (no debería haber hablado tan rápido en la entrevista).
     This sounds very natural and conversational, especially in Latin America.

2. With an infinitive, without “que”

   • Siento no haber hablado más despacio en la entrevista.
     Literally: I regret not having spoken more slowly in the interview.
     This focuses more directly on the action you regret. It’s a bit more compact and can sound slightly more formal or written.

In everyday speech, siento que + clause is extremely common. The version with no haber hablado is also correct, just somewhat less colloquial in many contexts.

Whether siento que takes the subjunctive depends on the meaning and who the subject is.

1. When siento que means “I’m sorry that…” about someone else’s action, subjunctive is common:

   • Siento que hayas tenido problemas. – I’m sorry that you’ve had problems.
   • Siento que no puedas venir. – I’m sorry that you can’t come.

2. When siento que means “I feel that / I have the impression that”, it normally takes the indicative:

   • Siento que esto es injusto. – I feel that this is unfair.
   • Siento que no debería haber hablado tan rápido. – I feel that I shouldn’t have spoken so fast.

3. When you talk about your own action as something you regret, many speakers actually prefer the infinitive:

   • Siento haber hablado tan rápido.
   • But Siento que no debería haber hablado tan rápido is also common because it blends “I feel that” with a judgment about your own past action.

So here no debería haber hablado is in the indicative conditional perfect (more on that below), and that’s perfectly normal after siento que in this meaning of “I feel that…”.

Debería haber hablado is a combination of:

• debería – conditional of deber (“should” / “ought to”)
• haber hablado – perfect infinitive (“to have spoken”)

Together, debería haber hablado literally means “should have spoken”.

In context:

• no debería haber hablado tan rápido = “I shouldn’t have spoken so fast.”

This form is used to express:

• Regret or criticism about a past action:
  
  • You’re looking back and saying that what happened was not the right thing.

Compare:

• No debo hablar tan rápido. – I must not / shouldn’t speak so fast (in general / now).
• No debería hablar tan rápido. – I shouldn’t speak so fast (general advice or present).
• No debería haber hablado tan rápido. – I shouldn’t have spoken so fast (past regret).

These forms all talk about duty/appropriateness, but the nuance changes:

1. No debería haber hablado tan rápido.

   • Sounds like a soft, reflective regret: I shouldn’t have…
   • Common when you’re judging your own past behavior.

2. No debí hablar tan rápido.

   • More direct: I shouldn’t have spoken so fast / I shouldn’t have done that.
   • Feels a bit stronger and more categorical, like you’re stating a clear mistake.

3. No debía hablar tan rápido.

   • Often describes a past obligation or rule (imperfect):
     
     • No debía hablar tan rápido en las entrevistas. – I wasn’t supposed to speak so fast in interviews.
   • Less focused on regret about one specific event.

In your sentence, the speaker is looking back on one interview and softly regretting their own behavior, so no debería haber hablado is a very natural choice.

Haber hablado is the perfect infinitive form:

• haber (infinitive of “to have” as an auxiliary)
• hablado (past participle of hablar)

A few key points:

1. Perfect infinitive = “to have done something”

   • haber hablado – to have spoken
   • haber comido – to have eaten
   • haber llegado – to have arrived

2. After debería (de), this lets you say “should have done X”:

   • debería haber hablado – should have spoken
   • debería haber estudiado – should have studied

3. The participle hablado does not change for gender or number after haber:

   • It’s always haber hablado, never haber hablada or hablados in this structure.

So no debería haber hablado is grammatically like “I should not have spoken.”

You might hear both:

• No debería haber hablado tan rápido.
• No debería de haber hablado tan rápido.

In practice:

• In much of Latin American Spanish, speakers commonly drop the “de” in this kind of sentence.
• Deber + infinitive often means obligation: Debes estudiar. – You must / should study.
• Deber de + infinitive traditionally expresses probability: Debe de ser tarde. – It must be late.

However, in real usage, especially in speech:

• Many speakers use deber and deber de almost interchangeably.
• In this specific sentence (about what you should have done), no debería haber hablado is more typical and completely correct in Latin America.
• No debería de haber hablado is also understood and used, but the “de” is not necessary.

Both rápido and rápidamente can function as adverbs, but:

• In everyday spoken Spanish, rápido is much more common than rápidamente.
• Rápidamente can sound more formal, technical, or written.

So:

• hablar tan rápido – perfectly natural, very common
• hablar tan rápidamente – correct, but sounds more formal or emphasized.

In Latin American speech, you will almost always hear rápido used as the adverb here.

Spanish word order is more flexible than English, but not that flexible inside verb phrases.

Natural options:

• No debería haber hablado tan rápido en la entrevista. ✅ (standard)
• No debería haber hablado en la entrevista tan rápido. ✅ (possible, but less usual; emphasizes “in the interview”)

But:

• ❌ No debería haber tan rápido hablado… – This sounds wrong/unnatural in Spanish.

Reason: tan rápido is an adverbial phrase modifying hablado, and the most natural position is after the verb phrase:

• haber hablado tan rápido

Prepositions with events can be confusing. Here’s how they differ:

1. en la entrevista

   • Literally “in the interview” → “during the interview” in meaning.
   • Focuses on what happened within the situation of the interview.
   • Very natural in Spanish for actions that happen in the context of an event:
     • Dijo eso en la reunión. – He said that in the meeting.
     • Me puse nervioso en la entrevista. – I got nervous in the interview.

2. a la entrevista

   • Usually means “to the interview” (direction):
     • Fui a la entrevista. – I went to the interview.
   • You wouldn’t say hablar tan rápido a la entrevista.

3. durante la entrevista

   • Literally “during the interview”.
   • You could say:
     • Siento que no debería haber hablado tan rápido durante la entrevista.
   • This is also correct; it slightly emphasizes the time span more explicitly.
   • En la entrevista is just more idiomatic and compact.

It can lean either way depending on context and tone:

1. “I feel that / I think that I shouldn’t have spoken so fast…”

   • You’re expressing a reflection or opinion about your past action.
   • Neutral tone, more like “In my view, that was a mistake.”

2. “I’m sorry that I spoke so fast…”

   • It also naturally suggests regret.
   • In context, especially if you’re talking about how the interview went, listeners will usually understand that you regret speaking so fast.

If you wanted to make the “I’m sorry” part more explicit about your own behavior, you could also say:

• Lamento haber hablado tan rápido en la entrevista. – I regret having spoken so fast in the interview.
• Siento haber hablado tan rápido en la entrevista.

But the original sentence already communicates both self-criticism and regret quite clearly.