Yeah I am a certified member of the itty bitty committee and am currently in a perfectly fit 34D, and my measurements would put me in 32DD.
Those letters just don’t really mean anything without the band size. Nobody, literally nobody, would look at me and think “D cup”.
Bras really need more than two measurements. I need the band of a 32-34, the wire diameter dimensions of a 34D and the volume of what I think of as a 34 B. I can find this in particular models of bras but it would be nice to have it on the label.