Eating issues

So ever since a few days ago I’ve suddenly had an obsession with how much I weigh. It’s all I can think about and I’ve been exercising and stuff to make sure I get to my goal weight. I’m 15 years old and weigh 49 atm but my goal weight is 42 (that used to be my average weight but I have gained some recently) Now after I reach 42 I know I will one hundred percent not want to lose anymore. I see myself as far though and for weeks maybe even months I have been skipping some meals. The thing is it’s not so that I lose weight that I’m skipping meals. It’s because I feel depressed. Like constantly I feel suicidal and I self-harm and a lot of the time I either just can’t be bothered to go and eat or I am feeling self-destructive. Idk why this is happening though. Or what is happening. Like I don’t think I have an eating disorder