She may have some physical issues and not sure where to get help or may be to embarresed even to go. She needs to find herself, it seems she is not comfortable with sex yet or may not understand it even. She might feel comfortable talking with a female therapist or even checking for some websites. Whatever her case is she is not comfortable talking with you it would seem. Jude30 brought up some good points too.

She tells you she don't know what she wants, maybe you could suggest looking for an online support group or something.

Sorry to say but either you have to be really patient until she figures herself out or keep pushing her until the relationship is destroyed.