I'm one of those rare women with a small band size, large cup size. . . wait. . . we're not actually that rare, but if you try shopping for a bra when you're one of us, you'll certainly feel like it! And don't even get me started on the size differences from brand to brand which make one brand's E cup fit me when another's G-GG won't even come close to being passable!
Anyway, while Googling bra-related queries, I came across a website called
Bra database | Bratabase & OMG, it's been such a helpful resource for me, you should all have a look at it! It has a size comparison tool from brand to brand, which is great for online shopping, & you can enter your measurements, current bras, how they fit, etc. & it'll develop recommendations for you personally, by utilising the data of all of us members who have contributed across the world. A fantastic effort, overall, by a very smart woman - highly recommended.