Why do I feel so insecure about me being BI?

I am truing 14 this July.. and I am bi. I am guy, and i feel so insecure, because I am more attracted to guys, how can i except who i am? my mom hates the idea that I maybe gay. I never told her, but she knows by the way I move and talk. She asks me if i am gay with her high pinched voice and when her eyes get bigger I get so embarrassed that I obviously say no.So yeah, should I come out to her or should I just wait, and ugh the hormones are so annoying!