I am not reading that.
well if she was bi-sexual then I believe devil man would have put that little piece of information in. So I will take it to mean she is a through and through lesbian. Give it up now dude is my advice if you chase her she'll reject you... However if she is bi-sexual and you don't know or if you want to test the water make a few jokes with her about the future and say "oh so whats next?" see what she says another reason to joke about is it gives the chance to say things that could cause offence to her or you without the offence, simply be subtle and that does not mean use a sledgehammer!
how old is she? she'll probably grow out of it unless she's already into her 20s or so, and even then it's still possible. of course it probably isn't worth waiting around for that to happen. Either she is a life lesbian in which case you have no hope, or she's a experimental lesbian in which case she probably has some gender issues and childhood stuff that makes her less than the most promising girlfriend material.
We already know that, we're just trying to find out who it is.
She likes your butt, not you.