I Am 5' 6" and 117lbs Getting Silicone. Torn Between 300cc and 325cc. Dont Want Too Big!

Every plastic surgeon has a way they help determine the best implant size for their patients.  I find the most proportional results are achieved by first measuring how wide the patients breast is.  An implant which is close in width to the patients breast and therefore fits the natural breast "footprint", will give a natural looking result.  At 5 feet 6 inches, you could look excellent with either size implant.  From your photos it appears likely your breast width is around 12 cm which is what the implants width is.   A change up or down of 25cc will only make a slight difference, so you could choose the larger implants with confidence they won't appear too big.  Silicone is a good choice and chosen by the majority of my patients for its natural feel.

Don't be nervous about a tablespoon and a half! And as I ask my patients..."Forget the word "huge" and if I have to fudge a little...do you want to be a tiny bit bigger or a tiny bit smaller? And it is true...99% of women wish they had erred on going larger than smaller.

Thanks for the posted photo. My guess and recommendation is go with the larger (325 cc) implant. Think larger due to decreases in size appearance after swelling goes down.