Calculate your BMI
http://www.nhlbisupport.com/bmi/that site should tell you if you are normal, under or overweight.
It depends if you have small bones or large bones. Medium bones...120-125lb.
truly everybody dont have to be the same size . it depends on how your body iz shaped. for example you can be slim and have very big breast and make you seem like you weight alot but truly your not, itz just your breast. and when you a teen, especially for a girl, most the time your weight go's up and down. there'z no Pacific weight your suppose to be, itz just how you jean poll iz and how your life style iz.