Hi love, whatever size implant you are thinking of having fill a jug with dry rice to the same messure as the implant size so if you want 460cc fill rice up to 460ml and if 525 fill to 525ml and so on, then put rice into the feet of old pair of tights cut off and tie. Place inside bra and see how it looks!
I found it quite help full when i was deciding, and i went with a much bigger implant and very glad i did. It wont however give you a natural look if thats what you want but it does help with size.
Hope thats clear.