I’m in year 11 currently and I understand exactly how you feel. But I am doing better now, and I think it’s probably down to the fact that over the last few months, people have done better than me on certain tests, or I’ve got things wrong, but then I’ve realised that it’s ok.
If you mostly get good grades, then why should it matter if somebody else gets a good grade, that’s maybe a little better than yours. I know it’s difficult. Just think about the end goal. Whether or not someone beats you by a couple of marks in a test, or you get something wrong in front of people, is not going to affect your future. Nobody can perform perfectly all the time. That’s just a fact. Don’t try to force yourself to. It doesn’t matter what other people are expecting you to get, if you’re still working hard.
And trust me, there are so many people out there like you. We’ll get through it.