Can anything help me lose weight?

I'm a 20 year old female and have always been big on exercising but have always been a few pounds overweight. No matter how hard I try, I can never seem to shed the 15 pounds that I want. My weight right now is borderline overweight according to my BMI so I know it should be possible for me to lose this weight but I can't. I've changed my eating habits overtime, and have a generally healthy diet and stay under my recommended caloric intake each day. I go to the gym at least 6 days a week and do interval cardio (fast pace with little rest time), long high intensity cardio( for at least 60 minutes), weight training, I've even ran 2 half marathons, and played sports all throughout high school and now college. I've tried so many different ways to try and lose the weight but I drop like 2 or 3 pounds and then gain 2 or 3 and lose back and forth for the past 5 years. Is there anything else I can, I'm nervous to try diet pills but I'm really all out of ideas...