Why am I not losing weight?

im in the 8th grade, 13 years old.. im 5'3 and 129 pounds.. ive been this since like november.. im not lazy at all.. i play 3 sports and even exercise on my own time.. i do hip hop abs and run on a treadmill occasionally.. i used to run 2 miles everyday but i was getting no results so i dont run as much.. i eat twice a day.. lunch and dinner... im a picky eater.. uhmm i eat a lot of fruit though.. i rarely ever eat junk food.. i only drink water.. i cant seem to lose any weight any body fat nothing... can someone explain this and give me some good tips to losing weight.. sites, your brain, anything pleasee help.. ive been trying to lose weight (on a diet) since about november december.. pleasee. thanks<33