yeah, ive met this type. Shes prolly very young and emotionally immature. She wants everything on her terms; essentially she wants you virtually committed and in control, but she wants the freedom to fck around (thats why she is resisting the title of girlfriend, because she doesnt want to feel guilty when she fcks with others)
You're best bet is to drop her, unless you can bang her out without attaching your feelings. If you get caught up, and it looks like you already are, you're gunna pay for it in the long run. Shes a ball busta.