Why Is 6 Afraid of 7?because 7...8....9.

I have never really been uncomfortable with my body. until now. i wear a size 7 (hence the joke.) my boyfriend, i know he loves me, but i know he doesnt really love my body. he is very into working out and fitness, he goes to the gym and he excersizes as often as he can... though not as often as he likes. he told me the other day "i dont know how to say this...but i wish you could lose some weight" i know im not fat, but im not thin either. and im not unfit, my legs are just as strong as his and i skate, and dance a lot. i really want to lose weight, for me and him, but i cant seem to do it. i used to skate to my school during the summer ( 8 miles) and now i cant because i dont have the time, and its too cold. i eat healthy and i dont eat a lot. but it seems that im always stuck at 125 -130 lbs i dont want to be 90 lbs, but i want to be a more aesthetically pleasing person. could someone help me find a way to lose 15 lbs? (im 18 and 5'1" by the way.)