If you haven't reached 18 yet, just work out, exercise and eat healthy. If you are 14, your body is probably going through a growth spurt and your frame is going to get a lot longer before you begin filling it out. I weighed 108lbs at 5'4" until I stopped wrestling during my senior year in High School. I put on 18lbs that year alone. The next year after High School I was weighing in at 125 to 130lbs.
Don't rush your body when it is still growing. Believe me, the weight will come. The sad part about it is that when you're 25, you are probably going to be going on about having to lose weight and you'll be reminiscing at the fact that you used to weigh so little.
It doesn't matter if you agree or disagree
... As long as I don't bore you and I spark a moment of thought, my goal is achieved
Queng leon queng tigre ecu tacacut, queca pa? - Pampangan Mandarigma Motto