[Hiraeth.]

It sounds like you are going through a really challenging time right now. Please find someone you can talk to, like a trusted adult. You might have to go back to the emergency room, and there's nothing wrong with that! Especially if it's going to be care that will help save your life. You should also consider finding a licensed mental health therapist to talk to about the things that are weighing down on you. Nobody self-harms for no reason, so there's going to be things that need to be spoken about with a professional.

You are far too young to be doing this. You have your whole life ahead of you.