When I was young, I used to mistake English for German and, of course, German for English.

I wasould trying to say a sentence in English and then there was my German mind would pop up, sabotaging all my efforts.

"I was trying" would refer to a specific instance.

I thought that it was me, that I was kind of broken and I wouldn´t be able to speak either language right to anyone of both.

Due to the number of people doing the same in English, the English course was booked up, so I had to go to private academies to prepare for an upper lever entrance exam and try it again.

Without the "for", this means that you were writing the exam.

Of course, when I speak or write I still make obvious mistakes and that is an aspect that II'm trying to improve.

The original sentence was correct but this sounds a bit more natural to me.

Deciding to resolve my confrontation with English opened a huge new world of documentation and resources that now I can explore, and that makes me proud of meyself.

I thought that it was me, that I was kind of broken and I wouldn´t be able to speak right anyone of bothright.

"speak right anyone of both" is not grammatically correct. If you have already said "anyone" you do not need to add "both.

I thought that it was me,; that I was kind of broken and I wouldn´'t be able to speak right anyone of botheither of them correctly.

Nevertheless, my German blood is still there; and thus, I´'m very hard-headed.

I decided that I would begin from the bottom,. I thought again and putgave myself affordchievable goals.

Affordable refers to money.

First of all, I enrolled in the German basic course at the EOI (Official school of Languages of Spain) in the German basic course.

The original sentence is also correct, but my correction flows a lot better in my opinion.

Due to the number of people doing the same in English, the English course was booked up, so. So, I had to go to private academies to prepare an upper -lever entrance exam and try it again.

Be careful to avoid run-on sentences.

Finally, I accomplished the little goals,. Now I´'m within the EOI for both languages in the EOI and I see the result of four years of work.

With doesn't really work in this context.

I can watch films in English,; the same withis true for books, podcasts or any content.

You need a verb in the second part of the sentence and a semicolon as the separator, since both parts of the sentence could technically stand on their own.

I see the same with gGerman.

All names of languages are capitalized.

Of course, when I speak or write I still make obvious mistakes, and that is an aspect that I try to improve.

Deciding to resolve my confrontation with English opened a huge new world of documentation and resources that now I can explore, and that makes me proud of meyself.