Should I go with 325 or 350 cc for my breast implants??

I am in between 325 and 350 cc silicone high profile implants. I wanted to go moderate but my doctor said that due to my thorax it would be best to go high. I am a big A cup at most because I don't fill a B. I want to be a C. I like the look of the 325 when I tried it on and I felt that 350 looked a bit too big on me. I also don't want to regret going too small. What would you recommend I do? My surgery is a month from now.