Am i fat???grrrr trying to fill up this space answers appreciated guys and girls?

so I am 5'3 121 pounds, 15 years old, and size like 4 or 6 jeans (american eagle). I felt so good about myself until I took a break from competitive swimming. I gained some weight from not doing hard practice and all my jeans are pretty tight. I feel self conscious and fat. And my skinny friends are always complaining when they gain 3 pounds. hey i was 115 a few weeks ago and now im a fatty. Idk do guys like skinny girls? is it ok to have a butt and thighs? idk help! also i feel like i have a skinny upper body and then from the waist down its just like ugh. anyways.