Thanks for the encouragement, had a bra fitting today, we used their private fitting area. I'd recommend it to anyone who prefers subtlety and discretion in all things.
fwiw, 42 was the answer. Apparently my concept of snug involves dislocating ribs and bruising skin. 42's made the available cup sizes a bit to large on top, but the underwire and lower supporting part of the cup are amazing. I could jump up and down without pain. She showed me the forms that would fill it out, and oddly enough they didn't look weirdly huge under a shirt. Honestly looked normal to my eyes for my current frame. I didn't get them because I do expect considerable reduction in band size over the next 12 months. (band crosses my Lats, which are substantial...)
WHEW! I did it! THANKS.
(and I didn't get treated like a space alien)