Get off the internet and find IRL help. Be that family, friends, and/or a mental health professional. The latter is highly recommended though.

Even without all the stuff you've got going on, 15 is often a tough age. Very few people have themselves figured out at that age. So my biggest piece of advice is to do your best, but don't expect to everything to make sense, and don't beat yourself up when life is messy. It's just the way it is.

Find a real life community, people who you identify with

Never take random advice from strangers on the internet.

Given that you're underage, I'm going to lock this thread before it gets weird.

I hope you can find the community and support you need, especially if it is offline.

Many people with tinnitus find that if they place their palms over their ears so that their index fingers touch behind their head, and then tap the bone there repeatedly with their index fingers, they gain some temporary relief.

I don't know if you have tinnitus, but I figure it can't hurt to know this. I'm not qualified to give life advice.

It's time to get into a band called The Mountain Goats

Therapy.

If you're trans, get on HRT as soon as you can. Most of the effects are not irreversible within just a few weeks, and if you have biochemical dysphoria that it alleviates that would be really great to know - also the younger you start HRT the better effects it can have and needs less surgery/money/dysphoria later. If you're cisfem though, you can disregard this.