I honestly think i'm going crazy.?

It doesn't sound childish at all. These are all valid concerns and stressors, honestly I don't really know what to tell you but I just wanted to let you know that it doesn't sound childish and that everything you're feeling is super valid. You are actually one of the more down to earth people on here. I would recommend not worrying about the weight issue and trying to focus more on looking as healthy as possible, that's what people tend to find pretty, try not to stress too much about that either though. Also if you're mom is not supportive try looking for support from outside of your family. I have the same problem, so I found support from adults who aren't related to me and it has helped me a lot.