Rachel,
I am 6 feet tall and a little over 200 pounds. My chest also measures 39 inches. I do not have implants, but I wear a size 40 D bra. Usually a Playtex 18 hour bra.
My feelings are that a D size cup on a 39 inch chest is not that impressive. Rather I look very normal and balanced.
If you are going for a larger breast size, you might want to go larger than the 550cc size. The last time I was in my plastic surgeons office, I tried on a pair of 600cc implants just tucking them in my bra. Yes I looked bigger, but not that much bigger. There are limits on how large you can go, depending on how much loose skin is in your chest area.
There are BA websites, such as "Implantinfo" and others with many before and after pictures.
The rice technique has been used for many years, but also many plastic surgeons have sample implants which you can tuck in a bra for a day or two, just to see how they feel.