How can I gather the courage to join my school's GSA?

I'm 16 and I think I'm a , but I've only told a few close friends about my attraction to girls. My school has a fairly large gay community. phobia is a problem but it's not widespread. Anyways, I'm friends with a lot of gay guys, but I only know two girls that are bi and they're totally off limits because they're good friends of mine. I really want to meet more girls like me but I can't find anyone to go to the GSA meetings with me and I'm too scared to go by myself. How can I overcome this fear and break into the gay world at my school?