You didn't mention if you have gotten and IOI's from her. Even with you being alpha in class and having great subject matter to talk about in class, you still have to pay attention to the basics. Have you even had any conversations with her that were on a personal level, not about the class? If not I'd say you may already be out of luck. Best chance you're only in the "student" zone which is worse than the friend zone. Worst case she sees you on the creepy side (which you point out in your above example about meeting 1 on 1 with her).
Couple ways you could play this still though. First - are you gaming any of the other 40 girls in class? If not then you've missed major dhv points and she's probably seen you as a poser alpha. I mean a real alpha in a sex class would be like a fat kid in a candy store. Next you would need to develop some trust with her. No way she is putting her future career on the line without trusting in you to keep it secret. How can she trust you without getting to know you?
Once you have those bases covered (her knowing you are sexually confident, can get girls in your class, and built trust with her and get to know her a bit as a person and not as a TA), then you could proceed. I personally would go for the route about needing her help studying. Something like "I know what to do in the bedroom to make a woman happy but all this studying and tests.. It's just not the same." Then be the strong alpha who's showing a little vulnerability and asking her for help. Be ready to switch back to alpha quick when she throws a test at you like "and I thought you said you know everything about sex" because a HB will call you on it. Keep it light and playful but try to get her to feel like she is really helping you with the coursework. It'll help with the feeling like she's maintaining control and let you build trust.
My feeling is if that goes ok you'll know if she's cool with helping you "study" one on one during the semester or if its best to wait until class is over.
Oh and if it doesn't work out, trying to game the TA of a sex class is bonus points in the eyes of the girl students, make sure you get extra credit for it!