Why the heck am I this way?

I usually take more time than the given one to complete a test. I used to do this even when I was in middle school, no matter what class the subject was. If it was for something like history or my native language, I would take more because I wouldn't have enough time to write the essays how I wanted them. If it was maths or physics, I would usually take exactly as the given time.

But now, I'm attending a harder lyceum and it's also so much more challenging (it's between a lyceum and uni). I noticed that here, on tests, I need even more time than I used to need.

Like I was doing my first math test and I didn't even have time to look at the last exercise, let alone even do it. Or on my chem test, there were just 4 problems, each one more difficult than the previous ones and we had 45 min to do them. Tell me why I didn't even have time to rewrite the solved problems from my scrap sheet, let alone read the last problem (worth 1/3 of the whole grade) and got a 7/10.

Or for history, we had 45 minutes to write 5 definitions and an essay, but the teacher did us dirty and gave us a half a topic and made us choose the other half that we wanna compare it to and it took me so long to think and arrange my thoughts, I didn't have time to write the essay how I wanted to and now I'm sure I'll get like a 6 or 7/10 (which is basically a failing grade here).

I hate this. I know when the problem is that I don't know the topic enough, but when I do know it, why the heck does it take me so long to write everything? It's like, my thoughts take so much longer to get to me then other students and it's so infuriating I can't even convey it into words.

I need to improve and FAST because if I get a final grade lower than 7.75/10, I will be expelled from the school and it's my dream school so I really don't want this.

I just don't understand why I take so long to think and to make up something from my ongoing thoughts.
Why the heck am I this way?
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