Stefanie,
Size is always a difficult one, as every girl is different. For my first BA I had 325cc and went from a 32c to a 32E. The 25cc deference between 325 and 350 is so small you won’t rain another cup size, maybe with 100+. If in any doubt talk to your surgeon and discuss you not want a bigger end result.
29 is narrow, so you don’t want super tanker boobs. Below are some details to help.
325 11.5 (4.7)
345 12.0 (4.9)
365 12.25 (5.0)
385 12.5 (5.1)
415 12.75 (5.2)
Cc/dia/projection
Cat xxx