Is this wrong or weird? he's 12, im 15?

It is wrong AND weird. You are way too young to even think like you are. Don't you have an adult that you can talk to about this situation? If you do not, go visit with a counselor at school or even a parent of a friend. It is purely infatuation and unhealthy. When you are 18 and he is 15 it will be statutory . Wake up!!!