I want to have sex

I’m 14 and I like this guy like a lot and I really want to have sex with him and stuff like that but the only thing is I’m really insecure about my body. I’ve tried loads of different ways to have a flat stomach but nothing seems to be working for me. I’ve even tried not eating as much but that does not help at all just makes things worse. I know the comments are going to be like ‘You’re too young’ ‘you should wait’ but I don’t just want a flat stomach for sex but for me. I hate my body and it doesn’t help when all my friends are drop dead gorgeous😍 which makes me even more insecure 🥺. Do any of you have any ways to help me not be so insecure? X