[¯|_(ツ)_|¯]

It's hard when we have expectations of where our lives would be and then things don't happen like we expect them to. It sucks, honestly. I'm like you, I didn't think I'd make it this far to be honest. But, we did. Both of us are still here for a reason, after all. We might not know what that reason is, but it's there.
Is there anything you can do to start building back trust with your parents? That may take some communication on your end, but maybe you can start by asking them for a cell phone if you don't have one already where you'd be able to text some of your friends from school. Then from there eventually maybe they'll allow you to have a friend over your house where you can supervise, or have an outing with a parent present somewhere. It may take some building up, and it may take time, but it's worth a shot!
I'm fat too, honestly. It doesn't mean you're a bad person just because you're fat. It doesn't make you ugly either. Fat and unattractive are not synonymous. Anyone who thinks it is isn't someone you want to be around anyway.
I'm sorry I don't have a lot of advice but I wanted you to know you're not alone.