Uvijek potvrđujem dolazak porukom, ali jutros još nisam potvrdila sastanak jer nisam primila točnu adresu.

This is mainly about aspect and time.

• potvrđujem is a present-tense imperfective form, used here for a habitual action:
  • Uvijek potvrđujem dolazak porukom = I always confirm my attendance/arrival by message.
• potvrdila is the past participle used with nisam to form the perfect tense:
  • još nisam potvrdila sastanak = I still haven’t confirmed the meeting.

There is also an aspect difference:

• potvrđivati / potvrđujem = imperfective, focusing on the process or repeated/habitual action
• potvrditi / potvrdila = perfective, focusing on a completed action

So the sentence naturally uses:

• imperfective present for a routine: I always confirm
• perfective past/perfect for one specific action not completed yet: I haven’t confirmed

Because the form shows the speaker’s gender in the past tense.

In Croatian perfect tense, you use:

• sam/si/je/smo/ste/su
  • a past participle

For I confirmed, the participle agrees with the speaker:

• potvrdio sam = I confirmed (male speaker)
• potvrdila sam = I confirmed (female speaker)

In the sentence:

• nisam potvrdila tells you the speaker is female

If the speaker were male, it would be:

• ...još nisam potvrdio sastanak...

Croatian often drops subject pronouns when they are already clear from the verb form.

So instead of saying:

• Ja uvijek potvrđujem...
• Ja još nisam potvrdila...

it is more natural to say:

• Uvijek potvrđujem...
• Još nisam potvrdila...

The verb endings already show the subject:

• potvrđujem = I confirm
• nisam potvrdila = I have not confirmed

You can include ja for emphasis, contrast, or clarity, but it is usually unnecessary.

dolazak literally means arrival, but in contexts like this it often means attendance / coming.

So:

• potvrditi dolazak = to confirm that you are coming
• very naturally in English: to confirm attendance

It appears without a preposition because it is the direct object of potvrđujem:

• potvrđujem što? → dolazak
• I confirm what? → the arrival / attendance

This is normal in Croatian:

• potvrditi rezervaciju = confirm a reservation
• potvrditi termin = confirm an appointment
• potvrditi dolazak = confirm attendance

porukom is the instrumental singular of poruka (message).

It is used here to express the means/method:

• porukom = by message / via message / with a message

So:

• potvrđujem dolazak porukom = I confirm my attendance by message

This is a very common use of the instrumental case in Croatian:

• autom = by car
• vlak om = by train
• telefonom = by phone
• porukom = by message

With a negative verb, još often corresponds to English yet or still depending on how you translate it.

• još nisam potvrdila = I still haven’t confirmed / I haven’t confirmed yet

Both are good English translations.

A useful pattern:

• još nisam + past participle = haven’t ... yet / still haven’t ...

Examples:

• Još nisam jela. = I haven’t eaten yet. / I still haven’t eaten.
• Još nije došao. = He hasn’t arrived yet. / He still hasn’t arrived.

So yes, još literally often means still, but in negative sentences English may prefer yet.

nisam primila is the perfect tense of primiti (to receive), and it means:

• I did not receive
• or in context, I haven’t received

It is formed with:

• nisam = I am not / I have not as an auxiliary in this tense
• primila = past participle

So:

• nisam primila točnu adresu = I haven’t received the exact/correct address

Croatian uses this form very naturally for a past event that is relevant to the present situation.

Also, primiti is perfective, which fits well because receiving something is seen as a completed event.

Here sastanak is the direct object, so it is in the accusative case.

The reason it looks unchanged is that masculine inanimate nouns often have:

• nominative = accusative

So:

• sastanak (nominative) = meeting
• sastanak (accusative) = meeting

That is why you get:

• potvrdila sastanak = confirmed the meeting

Compare that with a masculine animate noun, where accusative changes:

• vidim čovjeka = I see the man

But for inanimate nouns like sastanak, stol, film, the accusative often looks the same as the nominative.

Because adresu is the accusative singular of adresa, and the adjective must agree with it.

• adresa = nominative singular
• adresu = accusative singular

The adjective točna (exact / correct) changes too:

• točna adresa = nominative
• točnu adresu = accusative

So:

• nisam primila točnu adresu = I haven’t received the correct/exact address

This is adjective-noun agreement:

• same gender: feminine
• same number: singular
• same case: accusative

jutros means this morning.

It is an adverbial time expression, so it does not need a preposition here.

• jutros = this morning
• danas = today
• jučer = yesterday
• sutra = tomorrow

So:

• ali jutros još nisam potvrdila sastanak = but this morning I still haven’t confirmed the meeting

Croatian often uses these time words directly, without adding something like u.

Croatian word order is fairly flexible, but the given version sounds natural and clear.

Current sentence:

• Uvijek potvrđujem dolazak porukom, ali jutros još nisam potvrdila sastanak jer nisam primila točnu adresu.

Why this order works:

• Uvijek comes early to emphasize habit: always
• jutros sets the time for the second clause: this morning
• još nisam keeps the negative phrase together
• jer introduces the reason naturally

Some parts could move for emphasis, for example:

• Ali još jutros nisam potvrdila sastanak...
• Sastanak još nisam potvrdila jutros...

But these may sound more marked or stylistically different. For learners, the original order is a very good model.

They refer to two different things:

• dolazak = arrival / attendance / coming
  • potvrđujem dolazak = I confirm that I am coming
• sastanak = meeting
  • potvrdila sastanak = confirmed the meeting

So the speaker says:

1. In general, she always confirms that she is coming, by message.
2. Today, she has not yet confirmed the meeting itself, because she has not received the correct address.

In real-life usage, these ideas can overlap a bit, but grammatically they are different nouns with different meanings.