Numbers and stats aside I just want to say at 19 you should try and learn to love and respect your body, make healthy choices, don't get so focused on numbers.
Its easy for young girls to get caught up in wanting to be 5-10 lbs less, but will it really make you happy when you get there?
From a male perspective, we like curves, and we like confidence. 5'2" 106 lbs sound like a good weight to maintain to me but I'm no expert. For that height normal bmi is between 103-136 lbs.
Strong and sexy is better than thin and frail imo!
Exercising more causes your calorie needs to increase. Are you exercising daily? That could be too much.
If you want to harden your body try lifting free weights, especially squats. Barbell squats and other squat exercises will help shape your legs and reduce your waist size while building strong abdominal and core muscles.
I have posted that picture in other threads before, because this is what squatting will do for a womans body! She is lifting 225lbs!!! Thats probably more than you see most guys doing, and she is definitely not bulky.