Choosing a breast implant size is very difficult and a very important decision because once they are in, ideally you do not want to go back to surgery because all the risks associated with implants are 2-3x greater with subsequent surgeries. Your height will allow you to carry a larger implant, however 500 cc implants are quite large. Your tissue quality and the amount of pocket that you have will directly impact the appearance of the implant. Sometimes you need a bigger implant and sometimes a smaller implant to achieve the look you want. My approach to choosing the size is quite different. Since we do not know the elasticity of your tissue or how the implants will look until they are in place, I have patients bring in pictures of naked front view breasts to determine the look & size you are hoping to achieve. At the time of surgery, I have ordered in a range of implant sizes that will likely allow me to create the same look and then I use sizers to see which size matches your pictures the best. I do not use bra size as a reference. The make & style of the bra will affect which size you fit best. That is not the important issue, the important thing is that you see the breast size that you feel is ideal for you in the mirror when you look at your self naked, then you buy which ever style & size bra fits best. You can tell how the implant looks in your bra, but your tissue will flatten that implant once inside, you may find that the implant size necessary to create the size you like is greater or less than selected in the office. The biggest problem with my technique is it takes time and you pay for time. However, paying a little more once to do the job right, saves money and is a lot cheaper than paying a lower price twice to do it over.
Best of luck-
I hope this is helpful.