for me nothing's wrong with having sex while dating, but if it's not ok in your culture then I respect that opinion
Love's a powerful thing, and yes, love sometimes hurts. Sexual frustration too is pretty hard to deal with ('scuse the pun). She's obviously blowing hot and cold, letting you go part of the way but not all. Maybe she understands the effect that is having on you, maybe she doesn't. Maybe she gets off on leading men on, maybe she's just naive.
My suggestion is not an easy one but might be for the best. That's to seem less desperate, less interested and let her do all the work. If she really does want to go further, then she will. If she doesn't, then that's a sign to move on.