It doesn't sound to me like you're overweight. Don't forget, muscle weighs more than fat and if you're exercising a lot and running, then you are gaining muscle, which is a good thing! Muscle will be more dense, make you look more lean, etc. You need to make sure you are eating enough to keep up with your exercising and drinking plenty of water. Try and eat healthy, lot's of lean meats, whole grains, vegetables, and fruits, but don't get fanatic about it.