Sounds either like you are under too much pressure overall, or that you are a person that is especially anxiety prone.

Don't know enough to offer you great insite but I will tell you that "worrying" or "fearing" about anxiety magnifies it . Maybe, if you have done your reasonable best, you should feel happy and confident- no matter what the outcome.

I fell out of education early. I could not handle the pressure of intense study, but seriously if your doing your reasonable best to succeed, then you can not be expect to do more than that, and even if you FAIL, well, don't let academic benchmarks define your entire worth. I left school at 13, if I let academic success be my primary concern I would have gone crazy!