Why is she asking me this and what should i tell her?

She was being really pushy about personal matters and to be honest I think you should not tell her anything unless you guys are a couple. Its really private info that shouldnt be discussed with just anyone and I give you a lot of credit for sticking to your guns. As far as if girls care, its all a matter of the girl. Some do, some dont. Do you plan on starting a relationship with this girl? If not I guess whether shes a virgin or not doesnt really matter.