like they said, abs are made in the kitchen.
Your sports give you a good workout, so your muscles are working hard enough, but you definetely need to improve your diet. If you're not eating breakfast, DO IT--and make it healthy, since this seems like the easiest meal to improve....some whole-grain cereal with one piece of fruit is a good starter. If you like oatmeal, try some healthy oatmeal instead of the cereal. (I'm not talking about Lucky Charms or Cinnamon Toast Crunch, either....even those these are made with whole grains.)
-Add some ab training. Train them 3 times a week. For example, I go to a stability ball class at my local YMCA. You could also just look up ab workouts, but make sure you're not just doing plain crunches all the time....you should research ab workouts. (telling you to research is probobly not what you are expecting, but it's all I can do and its important to make the best use of your workouts!)
-I know that your sports, football especially, might have you training preety much all year round, but when you can, cross-train. Swim, jog, bike, play recreational soccer with friends, lift weights on your own. Do whatever you can do add variety to your muscles.
Hope this helps!