I am Carlos and I haveam 34 years old.

I have three sisters and two brothers.

I want to learn English because my eEnglish is not good.

Barcelona is nice city for going out to eat and to visit.

I want to travel a anto other´s countries but the problem is my eEnglish.

I must to work on it more.

I am Carlos and I haveam 34 years old.

I live in an apartament in Barcelona.

I have three sisters and two brothers.

Barcelona is a nice city for got to eat and visivisiting and going out to eat.

Saying visiting first and then "going out to eat" makes more sense because you visit first and then go out to eat.

I want to travel a anto other´s countries but the problem is my english.

"another's countries" implies you want to visit specific people in other countries.

I must to work more (harder).

Harder would sound good too.

Only I can trust meyself.

Not sure what exactly you meant here, but it's grammatically correct.

Thanks (or thank you), see you tomorrow

I a'm Carlos, and I have'm 34 years old.

Saying "I'm [name]" is more on the casual side, which is why using the contraction "I'm" is more natural
Alternative (more formal): My name is Carlos

I live in an apartament in Barcelona.

I have three sisters and two brothers.

I want to learn English because my eEnglish is not very good.

A bit more natural to say "not very good." The "very" softens the tone a little bit

My mother´'s name is Luisa, and we live together.

Barcelona is a nice city for going out to eat and visiting.

I want to travel a another´s countriesy, but the problem is my eEnglish.

"Another" does not need a/an before it, since the "a" is actually built into this word (an + other)
However, "another" is singular, so if you want to reference multiple countries, rewrite as "... travel to other countries"

I must to work more/harder.

We often say "work harder" instead of "more," when it's about effort

Only I can trustI have to trust myself / It's up to me.

A couple of more natural phrases

Thanks, see you tomorrow.