So confused...

Hey! Im a senior student in High School and I have always identified myself as straight. When I masturbate I think about guys and dicks and Im not really into having sex with a girl. However, since last year, this girl in my school told me: "I like your outfit!" and I said thanks and we never talked again. But I really felt something when I looked into her eyes and now I always have butterflies in my stomach when I walk near her. I follow her on instagram and I know her music preferences and she’s very beautiful and we have a lot in common. I’m sure I have a crush on her and idk why but I’d want her to know. She has a boyfriend so I really don’t know what to do it makes me sad 😞 Also I don’t know if that makes me bi... Im so confused!