When I was a teenyounger, I loved reading.

You could also say at what age specifically, for example, “when I was 15, I loved reading.”

I was mainly reading fantasy and sci-fi books which my mom and my brother were buying (had bought?).

But my passion for reading ended when I wentstarted attending university/going to a university.

I was livinglived in a dormitory and there always has been something else to do.

It was very useful in the beginning to help me in understanding some unclear parts.

I was mainly reading fantasy and sci-fi books which my mom and my brother were buying (had bought?).

But my passion for reading ended when I went to the university.

I got back tostarted reading more when I started learning eEnglish more seriously.

I didn't understand a lot of details, but I was still was able to understand the main plot.

The most difficult part was understanding descriptions of things since I didn't know many of the words used.

Now, I'm happy to be able to listen to audiobooks not only because I have to in order to improve my English comprehension, but mainly because I enjoy to dodoing it.

I was mainly reading fantasy and sci-fi books which my mom and my brother were buying (had bought?).

"Were buying" would imply that you were reading them as your mum and brother purchased them, whereas "had bought" would imply that you were reading the books they bought in the past

I could finish an interesting book in a couple days, because/as I would reading it non stop.

I was living in a dormitory and there was always has been something else to dohat had to be done.

Besides, I was surrounded by people all the time and it was pretty difficult to get some quiet time for myself.

I got back into reading moreagain when I started learning english more seriously.

You could use the word 'again' instead of 'more', as it shows you read in the past and are picking up the hobby again.

I was mainly reading fantasy and sci-fi books whichthat my mom and my brother were buying (had bought?)reading.

If you say "had bought" can imply they bought it for you. It sounds like you want to communicate it was books that were already around. So you could also say "had read".

So, I guess, I took up reading after them.

Aw that's nice. Be careful about excessive use of commas in writing.

I could finish an interesting book in a couple days, reading it non stop.

I was living in a dormitory and there was always has been something else to do.

The first book I read in English was "Dandelion gGirl".

In a title, usually most words are capitalized.

The most difficult part was understanding descriptions of things since I didn't know many of the words used.

Kindle has a nice feature that allows you to listen to the audiobook and follow the text at the same time.

I didn't know that!

It was very useful in the beginning to help understanding some unclear parts.