It is not possible to give you a medical opinion on your problem based on limited information and photographs. You need an in person consultation with an examination. However, it possible to make some general comments about what is typical or may be possible, but you should not consider these a...
I would suggest going with the 355 full or high profile implant than with an implant that is too wide for your chest. Long term, this will look better.
Generally capsules start to form within a few weeks after a breast implant is placed but like all scar takes a year or so to mature/form the final capsule. For a breast implant exchange it would depend if the existing capsule was removed or not. If it was removed then its a similar timeline but...
