Why do I have to wait until I'm 18 years of age to have my nose fixed?

When I was about 10 or 12 I broke my nose in a car crash. I am 16 now and my nose is bent and my left nostril is blocked because of my nose bending towards the right because it's broken. I really want a doctor to just break it back or set it straight but when I went to hospital when I was 15, the doctors said I will have to wait until I am 18 to get it fixed. They said that my face is still developing so that's why they wont do it. Would it be possible if I could get it fixed at this age?