If you are a girl of 13 years of age with a height of five feet and one inch then your normal weight is 101.63 pounds or 46.10 Kg. If you are a boy of 13 years of age with a height of five feet and one inch then your weight should be 44.95 Kg or 99.10 pounds. Your weight of 126 pounds or 9 stones is overweight whatever may be your sex.
I would not worry about feeling you are over weight. I am 5,1 and 9st at 21. At 13 I weighed a lot more about a stone and a half more, and the weight fell off as I got older. Do not starve yourself but mabey eat a bit healthier. As mums always say it is just puppy fat!!
I'm 8 stone 5 ft one inches and I'm 13 yrs old