Taking my body to the next level? What should I do?

Okay I have always been naturally thick as they call it. I have big hips and thighs. I eat healthy and do PT( im in the Army). Im not fat I just have these damn thighs and hips! Ive been excersing more in the evenings because I really want to lose 15 pounds I weigh 153 right now. It seems like Ive been at the same weight for months now. 153! I have nightmares of this number GEEZ! I cant lose it. I was talking to a guy friend about it and he says I have to push my body to the "next level". Just push myself in ways I never imagined. What does he mean? I feel like I will never reach the 140's range atleast. Thickness runs in my family is there really hope for me? Could I really change my entire body image even though Ive been like this all my life??? Please any suggestions, advice, motivation I'll take it all! Thanks!=)