Hi Avaa,
A couple of things. It feels like you are being a bit hard on yourself; I know this happens with a lot of students.
Also, the thing about grades. I didn't get great grades in my degree course and then at the end I got a very good degree. Another guy I knew got brilliant grades through the course and a lousy degree. It was all down to how we did the exams at the end.
I remember that students were always going on about grades and it took some pleasure out of the subject for me. I have enjoyed my subject much more since I finished university.
I hope you can ease up on the anxiety a bit, maybe some counselling would help. I think that health and peace of mind is the most important thing for all of us.
Goos luck, Myzen