White Spots On Teeth, And Alot Of Grey Fillings?

I feel a little self conscious of my teeth . Exactly two weeks from now, I will be getting braces! But , not the outside of the teeth that I am self-conscious about . Is the inside of my mouth? When I was a kid , I never floss my teeth! I brushed pretty good, but not floss. And that ended up biting me in ** a ! I went to the dentist , to know that had 12 cavities! I had not visited the dentist in about 5 years before ( not sure) ! They filled my cavities filled with gray, it looks terrible every time I open my mouth ! It makes me feel ashamed of my mouth ... Now I brush twice a day , flossing daily and I! Sometimes more than twice a day. Also, I have white spots on some of my teeth, I called decalcification. I know how I can prevent more of these points from popping up ? And , would you be able to replace my chambers gray , with white ? Can someone please give me tips on keeping healthy teeth, once I get my keys ? Please no silly answers ! Thank you ! = D