I'm not sure how much I'm able to understand English.

I have been studying English for more than 5 years.
I studied English when I was a student, though.
I can understand English now better than when I was a student.

I didn't like English then because I had to take English exams.
I didn't like to study English for the exams.
So I studied English, but I didn't try to understand English.

Now I like English and study English every day.
I read Harry Potter in English, watch videos about English on YouTube, write a diary in English and so on.
I changed my iPhone, iPad and MacBook's language settings to English.
There are no people that do such a thing, so they think that I am an odd person.
Whatever.
But I'm not sure how much I'm able to understand English.
I just wanna use English with people that can also use English.