So, my surgeon wisely advised me to ignore the cup size and look for the implant that would be wide enough at the base, where it sits on my chest, to properly fill that area to look proportional. So, given that goal, and how mine look now having used that as the only guide for how big of an implant to get, I would advise you to use that as your only gauge. Testosterone makes our chest walls larger than cis females, so if you go for just a cup size, you may end up with non-proportional looking breasts.