I don't want to mess with your motivation either way and it may just be me, but I never trust the feeling I get after an exam, either way. Sometimes I think I aced it and get a B, other times I think I failed it and get an A. Other times, I am right on the mark.
My best advice, and which I also still struggle with, is to walk out of the exam, let all thoughts of that exam go, and concentrate on the next one. Sometimes, it will just feel like a crap shoot.
Good luck to you on the rest of your exams.