I know how hard it can be, and I honestly survived by not having a social life at all throughout highschool. My gym friends were my best friends, so training also counted as “sociallising” for me.
I know that sounds crazy to a lot of people though so you just need to find what works for you, and a lot of times that does included sacrificing a little bit of your social life. Maybe decide on one party etc. that you really want to go to and work really hard in gym and school so that you can go without waking up the next day with a mountain of work you should have done the day before.
If you’re not a very organised person, you need to get organised. Time management is the biggest thing, and once you work it out for yourself it should get easier.
Make the most of it! x