I think my best friend is bi?

To start off, I'm bi. The reasons why I think she is bi is because she knows I like her and she does stuff that she knows will like turn me on lol and she kind of 'pretend' flirts with me. She does have a boyfriend. One night we got drunk and ended up making out and at some point said she really wanted to be with me and that she doesn't think she's straight anymore. I kinda think she likes me but is way to afraid to admit it because she feels that she has to be perfect for people (mostly her family) to love and accept her and being bi would make her imperfect. Anyways.... it seems like no matter how much we fight or no matter what I do to her she always comes running back like she hates being away from me. Of course we're best friends, but I haven't really been the greatest best friend... Maybe she can't stay away because she secretly likes me? I don't know. Can someone please help me out? Lol