I'm 5'5 100lbsis 300cc Too Big? I'm a 32 AA. (photo)

    300 cc in a high profile implant will not be too large.  Silicone implants would create less rippling.  Kenneth Hughes, MD Los Angeles, CA

I do not think your volume range of 300-350 cc is too aggressive, however silicone implants would be better in my opinion given your extremely little breast tissue.  Even under the muscle you will experience significant rippling laterally.  Good luck. 

The width of the implant selected should be based upon breast base width and amount of breast tissue already present, not your chest wall circumference.  Filling saline implants to the upper limit of what is recommended by the manufacturer will decrease the chances of visible rippling.  With high profile saline implants, however, this will significantly increase projection, and as these implants are all round, the more projection the implant has the rounder the final breast will appear.   If your skin envelope is very tight, a larger volume high profile implant may also increase the risk of creating stretch marks.

Placing implants behind the muscle provides camouflage and will decrease the chances of visible rippling in the upper / inner area of the breast (the region exposed when wearing a bra / bathing suit, etc.)

I would recommend reviewing your desires and concerns in detail with your surgeon.

To address your comment, silicone implants can be placed in women under the age of 22, but their use would be considered "off label", as the FDA has only approved the cosmetic use of silicone implants for women age 22 and older.