Why does everyone think im so skinny?

Okk im a freshmen 14 and I weigh 126 and im 5'6 1/2.... Everyone I know thinks I weigh like 100 pounds but I quickly correct them telling them my actual weight. Now don't get me wrong im not sticks and bones!! i have meat and stuff its just that I guess since Im like basically 5'7 the weight is spread out right??? Maybe because I have a flat stomach and wear a size 1 to 3 in jeans??? Sometimes I hate being so tall because I have to get all my jeans in long.. which I don't mind becuse I like my jeans to be long..But at the same time I guess I'm blessed because models are 5'7 and up and since im only 14 by the time im 18 i'll be at least 5'9,, maybe!!! So can someone please tell me that this just isn't me?? LOL