How long would it take me to lose 10 pounds?

im nearly 15. 5 ft2 and 110lbs. i would like to drop 10 lbs. i was wondering how long it would take me as it is like the last of the fat on me. i cant seem to keep it off. i have lost up to 6 lbs but it all comes back on sooner rather then later. i do average 3 hours of sports a day such as hockey or badminton. i average 1900 cal a day. i cant stop eating all togeather as pearents are watching. i do not have a ed. any suggestions? thanks :)