Hi MissInvisible, it does sound like your mum isn't very supportive but WE/I want to listen to you. And maybe we can't help you feel "happy" right now, because it sounds like you're going through a lot, but we might be able to help you lessen the pain/hurt a little.
And that's got to count for something- a starting point- considering where you're at right now hasn't it.......and then/from there.........there's nothing to say you can't be happy in time/gradually.
And just maybe letting out those feelings, talking about them, working through them can give you that same release hurting yourself might give you, but in a way that's going to help you/not hurt you.
So, just to be sure we're starting in the right place, do you want to talk about the urges/SI (because we want you to be safe) first, or about your feelings/what's going on for you first.

Alison