Am I unhealthy?

I'm 14 years old, 5ft 5inches and weigh roughly just over 8 stone. My spine curves inwards really badly, causing my stomach to stick out. I wouldn't call myself fat, but I see all the girls at my school who have flat stomachs naturally and I get so jealous. I know there are worse things in the world, but I get quite self conscious about it and think that guys won't like me because I don't have a super flat stomach. Any advice? Thank you!!
Am I unhealthy?
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