The advice I've found most helpful is NOT to worry about what 'size' you are. It's sooo different from brand to brand. Instead, go out and TRY ON a big variety of bras.. and focus on fit above anything else! Most women buy for cup size and don't pay attention to the band.. first things first, try on some bras in a smaller band size and bigger cup.
You need:
A tight-fitting but not too tight (should be very snug, but not uncomfortable) band, that doesn't ride up when you move around.
Straps that adjust to the perfect fit for your height, and don't pull on your shoulders.
Underwires that completely surround your breast tissue, lie flat against your body all the way around, and are completely comfortable (it's possible) - no pinching or chafing.
Cups that support you comfortably, that you don't spill out of, and that don't gap, wrinkle, or strain in spots.
It may take some time, but if you focus on these important requirements, you should be able to find some bras that are right for your very individual shape. Everyone is built so differently. For instance, I have very similar measurements to the OP (just at 30" above, 31" and a bit at fullest, barely 27" below) - and yet unlike her I am quite flat-chested, and my bras are all 30/32 A/AA.