You're still in high school, right?
When you leave high school (and I realize it might feel like it's a thousand years from now, but I assure you, it's not), you will meet a lot more lesbians and bi women. Which I suspect this girl is neither. But you're fixating because you have few options in your life.
So! What to do?
Talk to people. Meet people. Male people. Female people. Old people. Young people. Ugly people. Attractive people.
In short, start to reach outside yourself and your comfort zone. This will help you in two ways. (1) You'll have other people in your life and will not fixate as much on every little possible positive nugget with this girl and (2) you'll be in prime position to meet a woman who really is interested in you as a girlfriend.
Hang in there. It really does get better.