I need to lose weight FAST!

I’m confident in the way that I look and all, but I’m not a healthy size or weight. I’m 15 years old, 5”9 and 92kg!

Prom is in 5 months and I want to look good for this guy that I like. I know that I shouldn’t want to do that for him but I also want to do it for me. I’d be so much more confident if I just lost a bit off my stomach and my back. Other than exercise, anything I could do to be a bit healthier and see a change in my body? Thanks xx