Hi, I noticed it's been a few days since someone commented on this thread. How are you doing now?
I totally agree with what PassedExpectations said about trying to hang out with people. I understand from my own experience how hard it can be to 'put on a happy face' and go out with friends when you're feeling depressed, but I find that when I do, my smile eventually ends up becoming genuine. When you're around other happy people, you often can't help but become somewhat happy yourself.

It's also good to point out that people asking you to hang out means that they care about you and enjoy spending time with you. Try to remind yourself of that every time you're feeling particularly low about yourself.
Is there anyone that you could try talking to about the cutting and purging? Perhaps a trusted friend or family member, a trusted adult, or a therapist/counselor? It can be a big help to have someone else's support in getting through this, and you don't deserve to suffer alone.
Also, please try not to feel that by doing these things that you're somehow a 'bad Christian' or anything like that. I've guilt-tripped myself into that sort of thinking so many times I couldn't even
begin to count them. However, we have to remember that God will still love us despite having done these things, and I'm sure he will admire you for being strong enough to fight through them.
Take care and please try to stay safe <3