Hi Lu, you're obviously feeling vulnerable and frustrated, which might be why you're interpreting other people as not caring about you, or laughing at you or judging you. You know your Mum isn't laughing at you. She cares too much.
I'm sorry you feel so angry. Even if you can't control how other people react, you do have every right to feel it and talk about it. But please try not to hurt yourself, especially if you know it isn't helping.
If you feel like you have insight other people don't have, have you thought about writing your ideas and thoughts down, or making some art to express this? I find that's the only way I get any release when I feel like I understand things in a way other people don't and they don't get it when I try to talk about it.
When I'm feeling really aggressive I also try and do some tough physical activity, like press ups, to wear myself out (I'm really weak, I can manage about 4 at a time), or jogging on the spot as fast as I can. Could you go to your room and do that for a bit?
Ex nihilo nihil fit