i have actually mentioned my struggle to her multiple times. once, telling her that i thought i was bisexual. she brushed it off with "you're a hormonal teenager, you don't know what you're feeling. focus on school." and then later i told her i was really questioning my heterosexuality, and she said "it's normal. everybody goes through that." i really just wanted to tell her that i'm a lesbian, but i was afraid...she has a way of making me feel confused and insecure. i mean, i'm lucky that she didn't throw me out. things could have been much worse. but how do you deal with someone that just won't listen to what you're saying?
IMO, you should just flat out tell her you're a lesbian. With what you've told her before, I can see how she might think you're 'just' questioning, so she reacted in a way she felt appropriate. If you tell her you're gay and that's it, who knows? She might be wonderfully accepting, since she'll be able to tell you're sure about it. EDIT: If she has made blatantly homophobic remarks, I'd talk to the counselor at your school or someone similar before you tell her, just to have backup.
I agree with TwistyRainbow that you should (if you feel comfortable enough) tell your mother that you're a lesbian. I once said I was bi to my mom too and she didn't believe me. The second time I just flat out said that I was gay and that was that. She ultimately accepted it. Now, in my opinion, if you tell your mom that you're a lesbian, and your mom still refuses to take it seriously, I'd say drop it. You've already told her, and it's no longer your responsibility to actually convince her or make a big deal out of it. plus, if you feel like things could go bad, it would be good idea to not pursue the subject until you're independent/off to college...etc Not sure if this was a good advice, but I wish you good luck. Hope everything goes well for you.