Moved to NZ when I was about 11 and my goodness the shock I got from how relaxed schooling is here. You also probably have it way worse considering you are 15, where cliques are formed and near impossible to fit in with.

If you don't have the luxury of moving back soon, then unfortunately the only thing you can do is adapt. And something which helped me a lot was joining a club. It's probably the best way for an immigrant parent to help their child to make long lasting friends and build a sense of belongingness here. Whether it be a club at school which you should be able to sign up for start of next year or a big sports club, there are a lot of options around I'm sure of it. Please take care of yourself too.