It matters a bit how old she is and how old you are. It used to be rather common for women who wanted to be up-to-date to try lesbian relationships during college, and then sometime afterwards to start realizing that they didn't want to go thru life like that, but weren't sure they could adjust to being with a man. It is an unfortunate fact that intimate relationships are much more difficult between a man and a woman than between 2 of either sex--because not only is sexual harmony much more difficult to develop, but the gender differences between thinking and feeling habits are much greater than the normal individual differences between 2 people of the same sex. OR, if you believe that one purpose of couple intimacy is to deal with SO MUCH intimate friction that you have to develop your personality MUCH further beyond your own self-centered understanding of what it means to be human and how much you need to bend your own desires and acceptance and empathic capacities to make life tolerable and often happy with an intimate partner who'll never really be the same person as you. And in this Jewish girl's case, will also NEVER want to hide her own thoughts or feelings just to make you think she's happy with you the way you are.
You sound like you're about 22 at the oldest, and she's driving you crazy, with not knowing what she wants. I'd suggest that you don't need to blame yourself if you can't make this relationship develop the way you think it should. And if you feel sorta rejected way too often because she won't make love with you--I wonder if you're afraid to make any first moves toward her--because learning how to be more passive isn't going to do you any good with women in the future. For they like a guy to take the risks of starting activities and even sex for them, and young guys without much experience usually don't want to risk getting told NO.
Couple questios: Do you think there are SPECIAL characteristics (or interests or activities) of YOURS that she's excited about? Or is it possible that you're just a GUY that she can try out to see if she ha what it takes to make a guy want her, so she really does have a choice of which gender she wants to have love with? And what are the Special characteristics (etc) about HER that are attractive to you (NOT counting looks!)--and also not counting that perhaps she came on to you first?