You are a tough one. Okay, do you think if she was a bit more forward you'd be comfortable with that? Maybe it's harder to read the signs because you're a nice guy who doesn't come across as arrogant? But seriously, maybe you should write down a checklist. If any of the first 6 were achieved your onto something.
I'd write down a check list. Then again, I'm no longer a prof haha - homework was never my thing, whether it was as a student or as a teacher
I've dated one of my professors after he was no longer my professor and I think what I liked about him is that he was insanely smart and very well spoken...not to mention fucking hot. Plus they tech you stuff and when you have to talk to them during office hours it's like they're interested in every single thing you have to say. The guy I dated though turned out to be a total jerk and was THE most immature person I've ever dated.