Ready for a Redo, confused about cc's

So confused about size. Im 5 5 150lbs currently have 650cc above the muscles. in Bras im a 34 D in Bali bras and in VS im a 34DD. I think im big for my size but not huge. Im having a redo / lift next month and im having an issue with size. I showed my PS a picture and he recommended 500 ccs. 500 seem big to me but if im currently a D could a 500cc under the muscle possibly bring me to a C ?. I was thinking 450 CC dropping me 200 cc which should give me a noticeable difference. Im still confused as to how some women have 450cc and they can be a DDD but how can I have 650cc any only be a D. So confused at what size I should downsize to