"The fact that retail shops simply do not carry band sizes under 32 is seriously a problem."
This! I went around wearing 34B for years until the back pain got unmanageable. Got myself measured, got told I was a 32C. Hard enough to find in stores but they had a couple. Still had back pain though. Measured myself and ordered bras online- 28DD fits great, pain reduced, yay! (Not anymore, they got bigger. :( )But the fricking saleslady couldn't tell me that I was a 28 anything cuz of course they don't stock it. Buying bras is this crazy ordering and returning ordeal and I hate that they don't last forever so I have to do it more than once.