What happen that I don't write here?

Well I was thinking that as I was on holiday I would be more free to practice languages and write in English.

That’s what I’m doing.

It’s pointless to repeat the same thing twice here.

And I think my English isn't good, but isn't bad either. / Suggestion: And I think my English is average.

So I think I can start to focus on other languages while I try to improve pronunciation and grammar in English.

I just have one more month of holidays because next month in September I will start college!

I would write, “I have only one more month off, because...”

I’m really excited.

I don’t think that your original sentence here sounds natural.

I'm doing well with my Portuguese; I'm learning a lot.

However, I can't find music in Portuguese that I like it.

If you want to use “although,” you have to connect it with the previous sentence. When you use “although,” both aspects of your statement (positive and negative) have to be in the same sentence.

“...I’m learning a lot, although...”

I mean, I found good music, but it isn't the type of music you can listen to all the time.

I'm thinking of writing in Portuguese soon, but I don't know.

pensar en = think about.

While I’m at it, I’ll save you another mistake that Spanish speakers often make:

soñar con = dream about

My next target language is Russian, but I'm thinking about studying Esperanto too.

And of course as soon as possible I will study French. Whenever I hear this language all I can say is 'AMAZING! WOW'.

Or, “Wow; amazing!” would also be a natural order.

I like the sound of Portuguese sound so much too and the Brazilian 'sotaque'.

Russian for me will be difficult because it has a different alphabet.

But while I'm learning Portuguese, I'm learning the Russian alphabet too.

In this way, when I will study Russian I will [already] know about it's alphabet.