More than likely you are not eating enough for the amount of energy your are using through exercise and development. Many athletic teen women need as much as 3,000 calories to support both. If you are not eating enough, your body stores energy to be sure it always has what it needs. Use this article to help you assess your intake or use the tracker for 3-5 days and see where you are coming out on average and then make adjustments from there.
A Teen's Guide to Nutrition & Healthy Eating
What You Need to Know about Nutrients, Calories and More teens.sparkpeople.com/resource/nutrition_a