Your crush seems to want you to put more of your feelings out there. She's flirting with you but what kind of signals are you sending? You're having your best friend talk to her on your behalf. No wonder she's sending you conflicting signals. Communicate more directly with her and leave your best friend out of it.
The only real way to know how she feels is to ask her. She’s asked you to prom already which is a big deal so you need to follow up with her to clarify. Tell her you’re looking forward to going to prom together if she’s still interested and you would love to go as dates rather than just friends. Ask her what she thinks about that. Then be quiet while she gives you her thoughts. If she doesn’t think of you in a romantic way, she’ll let you know immediately and then you can recalibrate expectations accordingly. You can do this.