I have found that anything over 38 is where it becomes hard to find a bra with a B cup (B is just the size I prefer); however there are 40B's out there, but the choice in style becomes very limited. I have also found that the choice in 38B is somewhat limited, but not as bad as the 40B; however the 38 is a bit on the tight side for me and I am not a big fan of bra extenders. Eventually, I purchased one from Victoria's Secret that was stretchy enough to where it feels really comfortable. It is a satin padded bra with embroidery around the cups. It looks as good as it feels. I now have 4 of same bra, and when it comes out in different colors, I am always tempted to buy another.
Patricia