Very good writing. I have a few suggestions/corrections below:

Post-adolescence crisis.

Having finished high school [only] one semester ago, I've already started a new life. New city, new career and new friends. (adding "only" will help give context to "already", saying you've already begun a new life despite only finishing school a short time ago)

Living by myself these last six months was more scary than I thought it would be. I still can't believe that I already started my university life and the fact that I just left behind a part of my life full of memories and good moments.

Am I happy with that [decision]? (optional to add decision, but it will help make it clearer) It's hard to explain. It's a mix of emotions. Sometimes I feel happy for gaining some autonomy, for taking care of new responsabilities, but on the other hand I feel frightened and indecisive at the same time. (both "on the other hand" and "at the same time" are colloquialisms, as far as I know those sayings stay the same in every context that you use them) 

After all these changes in my life it's inevitable to that I will go deep on into my thoughts and ask myself about the future and why not the(??) my overall existence as well (I'm not sure if that's what you mean?). The truth is that I am not sure if I am making the right choices anymore. I am not sure what I want to do in the future, and even worst worse I am not sure if I like what I am doing right now.

Having a couple of friends who have already dropped their studies and don't have a clue as of what to do next makes me think even more. The only thing that I am sure these days is that if money wasn't a problem I would get away from this life as fast as I can, without doubting it for a second.

This is really good. It's a difficult, existential, philolosophical entry that makes use of a lot of complex sentence strucutres, not to mention abstract thoughts and conclusions. I say "hang in there!" your English is very good and you should keep working hard if you can. Do as great as you can in school and try to make it through, learning as much as you can. Good luck!

Post-adolescentce Crisis.

Having finished high school one a semester ago, I've already started embarked on [my preference] a new life. Living in a new city, having a new career and making new friends.
Living by myself like this for the last six months was a bit more scariery than I thought it would be. I still can't believe that I already had started my university life and the fact that I had just leave left behind a part of my life that was filled full of with memories and good great moments.

Am I happy with this that? It's hard to explain. It's a Just one mix bag of emotions. Sometimes I feel happy for gain some of having independence autonomy, for taking care of with new responsabilities to shoulder but in on the other hand, I feel frightened fear and indecisiveness at the same time moment.

After all this With these changes in my life, it's inevitable to go be in deep on my thoughts and to ask myself about the future and why not the my very existence as well. The truth is that I am not sure if I am making the right choices anymore. I am not unsure of what I want to do in the future., and even worst Worse still - I am not sure if I like what I am doing right now.

Having a couple of friends who had already dropped their studies and don't have no a clue of what to do next of the next step, it makes me think even more. The only sure thing is that I am sure these days is that if money wasn't a problem no object, I would get away from this life as fast as I can, without doubt it for a second having to think twice.