34B, would like to be 34D. Would saline 500cc moderate plus profile be a good choice for me? 5'7" 140 lbs. (Photo)

I recommend seeing a plastic surgeons to discuss the different options for breast augmentation.  Bra cup sizing is not an accurate way to choose a size because all D cups are not the same.  Also, everyone has a different definition of what "natural" is.  There are different ways to choose a size.  I like to look at patient's "wish" photos. 

Many factors weigh into your final size and appearance. Your fold diameter, rib cage anatomy, and type and amount of breast tissue will be factored. Seek consultations with Board certified plastic surgeons in your area.