How can i convince my doctor to give me medication/supplements for increasing bone m?

I went to my general doctor one day and I asked him that I wanted to increase my bone and body m and was wondering if there's a special diet he can put me on or something I can take. He didn't really give me a straightforward answer, so it didn't help much. But after doing some research I found out there is medication and supplements that can help increase my bone m. When I was a newborn my mom had trouble feeding me so I didn't get the proper nutrition I needed and my bones are unnaturally thin for my age. I do exercise, I lift and I recently adopted swimming(I'm a lifeguard now), and I also eat a heavy protein and calcium diet. But I only see an increase of muscle m and my bones are still thin. I really want to do as much as possible to increase my bone size. I just turned 18 and my body/bone size is too thin for my age. So what can I do to make my doctor give me supplements/medication? Would I have to go to a nutritionist or pediatrician?