well dont you worry at all, instead try to channelise your energy in productive activities, like sports, for eg, outdoor activities, and try to meditate for sometimes, and concentrate on your studies. although it is quite natural at your age to indulge in masturbation,but as you know, excess of anything is bad, so once a while is not a problem, but more harm is done by giving more attention to the problem, so once you remove your attention from your physical momentary problems, and start paying attention to your producive activities, you problems will go away. wishing you all the best.