475cc Saline to 600cc HP Gel - Too Big?

AT your less than average height, I would not recommend the 600 cc implant without a discussion of the long term consequences. Without trying to sound too insulting, a very large implant (600 cc is) can make a shorter prson appear more heavy and you will be pressured to remain thin or wear garments that exaggerate your waist and crate an hourglass figure in order to avoid the appearance of a round midsection

Breast implant size is a very individual decision with multiple variables. These include, height and weight, chest size, and pre-existing implants. It sounds like you already have large implants in place and are small framed. It is unclear why you want to change the implants out, but likely you have stretched out and your breasts have thinned and sagged with the large implants. Commonly the thought is just put in a larger implant which it sounds like you have been recommended, though likely you need a breast lift with a size appropriate implant. Consider a second opinion because some decisions will prove costly and irreversible.

Going to a 6600 may be too big.alot depends on the amount of soft tissue you have.If the soft tissue over your incision is thin and you are a smoker you could be setting yourself up for an implant exposure.Soemtimes this tissue is so thin and then the patient smokes and look out so i would say be cautious.