Llevo escrito el primer párrafo del resumen, pero todavía no he elegido el título.

This is a very common learner question because llevar normally means to carry or to wear, but here it is part of a different structure:

llevar + past participle

In this pattern, it means something like:

• to have done so far
• to already have completed a certain amount
• to be this far along with something

So llevo escrito el primer párrafo focuses on progress: the speaker has reached the point where the first paragraph is done.

It is less about the single act of writing, and more about how much of the task has been completed up to now.

Because llevar + participle and haber + participle do different jobs.

• he escrito el primer párrafo = simply states that I have written it
• llevo escrito el primer párrafo = emphasizes that this is the amount completed so far

So llevar adds the idea of progress within a larger task.

In this sentence, that makes sense because the speaker is talking about two stages of writing the summary:

• the first paragraph is already done
• the title has not been chosen yet

Yes, absolutely.

That would be correct Spanish, but the nuance changes a little:

• He escrito el primer párrafo del resumen = I have written the first paragraph
• Llevo escrito el primer párrafo del resumen = I have the first paragraph written so far / that is what I have completed so far

The version with llevo sounds more natural when you want to show partial progress in an unfinished piece of work.

Because the past participle of escribir is irregular.

• infinitive: escribir
• past participle: escrito

Many common Spanish verbs have irregular past participles, for example:

• hacer → hecho
• ver → visto
• poner → puesto
• romper → roto

So escrito is the correct form here.

Because primero becomes primer before a singular masculine noun.

This shortening is called apocope.

So:

• el primer párrafo
• el primer día
• el primer capítulo

But if the word stands alone, you use primero:

• Es el primero.

The noun párrafo is masculine singular, so primer is required.

del is the contraction of:

de + el = del

So:

• el primer párrafo del resumen = the first paragraph of the summary

This contraction is normally mandatory in Spanish, except with proper names or certain fixed expressions.

For example:

• el libro del profesor
• la portada del informe

This is especially relevant for learners of Spanish from Spain.

In Spain, the present perfect (he elegido) is very common for actions connected to the present, especially when the situation still matters now.

Here, the title has not been chosen yet, and that unfinished status is still true now. So todavía no he elegido sounds very natural.

In many parts of Latin America, people might more often use the simple past in similar contexts, but in Spain the present perfect is often preferred in this kind of sentence.

Yes. In this sentence, todavía no and aún no both mean not yet.

So you could also say:

..., pero aún no he elegido el título.

Both are correct.
Todavía no is often a little more common in everyday speech, but both are standard.

In this construction, llevar + participle, the participle often agrees in gender and number with the thing that has been completed.

Here, the completed thing is:

el primer párrafo
masculine singular

So the participle is:

escrito
masculine singular

You can see the agreement more clearly with other nouns:

• Llevo escritas dos páginas.
  because páginas is feminine plural

• Llevo hecho medio trabajo.
  because trabajo is masculine singular

This agreement is one of the clues that this is not the normal perfect tense with haber.

Both can talk about something already written, but they do not feel exactly the same.

• llevo escrito emphasizes progress so far
• tengo escrito emphasizes the resulting state: it is written, it is done

So:

• Llevo escrito el primer párrafo = this is how far I’ve got
• Tengo escrito el primer párrafo = I have the first paragraph written

In this sentence, llevo escrito works especially well because the speaker is describing progress on an unfinished assignment.

Because the speaker is referring to the specific title of that summary.

There is only one title being discussed: the title that belongs to that summary.

So the definite article is natural:

• el título

If you said un título, it would sound more like a title, any title, one possible title, not the final specific one.

Yes, it is standard and natural.

Pero joins two contrasting ideas:

• one part of the work is done
• another part is still unfinished

In Spanish, a comma before pero is very common when it links two full clauses like these.

So the punctuation here is normal: ..., pero todavía no he elegido el título.

Yes, a little.

For example, you could say:

Llevo escrito el primer párrafo del resumen, pero no he elegido todavía el título.

That is also correct.

However, todavía no he elegido is very natural because todavía no commonly goes before the verb phrase. It sounds smooth and is probably the most neutral order here.