Having been on the pill for a few months now, I am proud to report that my breasts have grown from 32-no-one-makes-cups-this-small-dammit, to 32-a! The past few years I've mostly worn training bras from Target, which come in a few cute colors and patterns, but are lacking in the won't-show colors of black and "nude," and have oddly-placed underwire. Now, I have one black bra and one "nude" bra that came from the adult lingerie section. I have arrived.
I still don't like my bra selection, though. Bras this small usually have a metric buttload of push-up padding, because most bra manufacturers seem to think that a-cups are something to be ashamed of. I stopped wearing padding after meeting Wulfy, who helped show me that my breasts are fine as they are, thank you very much. Victoria's Secret even has a bra they claim "fit's like custom," which means that d-cups have no padding and a-cups have more padding than I have breasts. And their underwire stabs me like woah.
I also don't like going braless, which larger-breasted women keep marveling at--even though they're small, it's uncomfortable to jog or go down stairs without a little support because they bounce (that, and my boss is the Abominable Snowman who keeps the office incredibly cold and a ridiculous lot of people are offended at the site of a nipple bump through clothes). This, even though my mom had to naaaag me to start wearing a bra when I was thirteen.
I'm more-or-less happy with the way my boobs are now (I was not particularly happy when they grew, as now I only have two bras I can comfortably wear), I just hate whatever idiot designs most bras.
Now, a couple sources for small-sized lingerie. I haven't ordered from these yet, but at least most of the models do actually have small enough breasts that I can get an idea of the fit on petite ladies like me:
Lula Lu petite lingerie has lots of cute lacy styles, and lots of basics.
The Little Bra Company has bras designed by a petite woman just as frustrated as I am about bra design.