It can be hard to work up the courage to talk to girls but if you put yourself out there people will respond. For me, personally, I still feel like I'm not in a place where I physically feel comfortable enough to be in a proper relationship. For me, that's not happening until I get top surgery. However, that doesn't mean I don't flirt. I've also gotten a few girl's numbers passed my way in bars and so on. That helps with confidence just knowing people are interested, but they're not aware I'm trans and that's where I get hung up myself.
Confidence is more an act than real anyway. Very few people have legit confidence without them being otherwise cocky, which isn't an admirable trait. The best way to appear confident is to imagine yourself as a confident person and then act it out. The only thing to watch for, obviously, is that slip to cocky.
However, I agree with what others have said here. Actively searching for a girlfriend just to have someone on your arm at homecoming isn't the way to look at it. You can go to homecoming in a group of folks or go with a guy or girl as two single friends. I went to prom with a group and there were some within that group that were dating, but not all. The idea was that even if folk were dating that we'd still stick as a group anyway. Maybe you can suggest that with your friends and add some other single girls and guys to the group to even it out so not everyone going is dating.
Either way, when thinking about dating or asking someone out, it should be for more than arm candy. You're still young so you can shop around a little but finding someone you have something in common with and there's a mutual respect for is the goal over just not wanting to be alone.
And the irony is that when you're desperate for something, you struggle to find it. And when you're not actively looking for it, it'll find you.
