i second the bravado lifestyle suggestion. it actually seems to run a bit small in the cup, so you may even need a C. also, the original bravado can be special ordered in an XS from their website, but i think when i was checking into it, it only comes in white if you get the XS. i would check out
breakout bras, they have a few bras in Bs. another brand i LOVE (i wear it every day) is
bella materna. their bras are more on the petite side as well. i love the ruched clip bralet. that bra has a 32B, and then everything else for that style (34 and up) is a C or bigger, but you could always do a 32B with a bra back extender, and it would be the same in the cup as a 34A. the
ruched clip bralet is really stretchy too. i've been wearing mine for a year now. when i bought it i was a large 32D, and now i'm a pretty middle of the road 32C, and it still fits fine. (and when my large breasted nursing friends see it, they're totally jealous that i can wear such a pretty nursing bra
: i guess that's one good thing about being a hard to fit small when you nurse!
)