My observation is that bullies bully, because they're insecure about their own worth. They try to make themselves feel better about themselves by putting others below themselves. The more worth they perceive in you, the more they want to put you below themselves.

The vile thing about your age is that pretty much no one has much actual worth to show for themselves. You're still going to school, so you haven't yet achieved much for society. When you get out of school, you'll still have plenty time to achieve things for society, but it can still make people feel bad about themselves until then, and some of them react by bullying.

So, yeah, basically two things:

1. It will get better. Adult bullies are quite rare, because adults generally have self-worth.
2. Try to make friends. Bullies won't go after you, if they feel like many others are on your side, because those others are your (mutually relevant part of) society. They can really shred those bullies' self-worth.

If you're struggling with proper friendship, this does not need to be proper friendship. It can absolutely be transactional, like maybe you can explain certain subjects to them or heck, bake cakes, and they'll do the emotional work of integrating you into their friend group.