You mentioned that as far back as elementary school you have felt picked on by teachers. I think you were probably had one or two bad teachers early on, and became conditioned to expect certain behaviors from your teachers. Because of this, you might be quick to read into situations, and may react in a way that really does offend the teacher, who then really does treat you unfairly, and the problem continues to escalate over the semester or the year.
The best thing you can do when you think you?re being treated unfairly is to be calm and courteous, and to talk to the teacher (and I mean really talk to them, teachers need ALL the details). When your math teacher refused to give you the extra credit points, you needed to explain why you had to leave class early that day, and that you emailed a classmate to get the missing notes (which shows responsibility). When she gave you a B instead of an A, and gave her story about how she grades ?differently?, unless that story was backed up in your syllabus, you should have reported her to the dean?s office and challenged your grade. You have rights as a student!
Cheating is rampant is secondary schools and colleges. There?s no specific type of person that cheats. High-achievers, low-achievers ? they all cheat. Your professor has not had the opportunity to really get to know you, and all she sees is a person that was at the bottom suddenly jump to the top, so a little warning bell goes off in her head. How she handled it was passive-aggressive and unprofessional. If she thinks you?re cheating, then she needs to have a face to face conversation with you. In this situation, I might think about meeting with my academic advisor and explaining the situation. Mention you don?t mind testing separately from the other students, but you do feel you are being singled out and you?re worried about being graded unfairly. Your advisor can let you know what your options are.
I hope this is helpful.