yea that sucks, not gonna sugarcoat it. Being stuck with people you don't even like at school is the worst. But honestly, school is just a small bubble. Just because those people think your interests are "weird" doesn't mean they actually are, they just don't get it.
Also the girlfriend thing, don't even worry about that right now. You're 13, most people your age are just messing around anyway. For now, just focus on your own stuff and don't try to force friendships with people who treat you like shit. Like @tulip swan said, a lot of people your age are just trying to act cool and talk about girls all the time. That's just how it is right now. You don't have to be like that. Half of them are just following each other anyway. If your interests are different, that's not a bad thing, it just means you're not copying everyone else. It won't stay like this forever, it just feels like that right now. The right people come later, not always in your current class.