I loved reading Andrea's advice for finding plus size long line bras. However, I happen to be at the opposite end of that spectrum. After seeing a few comments requesting a “minus size” round up, I thought it was time for me to step in and represent those of us who are not as, erm “well-endowed.” (FYI this post has pictures of ladies in their undergarments so it's probably NSFW.)
Buying bras can be quite tricky. I want a bra that supports and shapes, but I really don't like padding. Although I may be smaller chested, I'm proud of what my momma gave me! I don't like all these fancy schmancy water bras and miracle bras that add two cup sizes! No thanks — I'm all real, baby. The problem is that most bras for smaller chests are super padded.
Right now I own the Multi-way Bra from Victoria's Secret. I liked it because the cup is lighting lined and there is no padding. However, without straps this proved problematic. The band stays in place, but the actual cups are so flimsy that they slip down all the time, which means wedding day nip slips and weird square boobs. No one wants that!
I've tried a few strapless bras with no luck. I tried on the Le Mystere Women's Shameless Strapless Bra but didn't like how it felt like a shelf yet it did no lifting. The bra practically swallowed my chest. Also the Natori Memory Convertible Underwire Bra fit well but it had seams that totally showed through my dress. Not to mention it felt very constricting.
However, my new favorite strapless bra is the Calvin Klein Perfectly Fit Strapless Bra. This bra is great for most strapless style dresses. The cups are lightly lined with only a tiny bit of padding at the bottom. That padding helps lift to create a more rounder and fuller shape. Also, the band stayed up really well. I haven't worn this one yet but I did a few jumps and twirls in the dressing room to test it out. No slippage! (Which you should totally do if you're going to be dancing at your wedding.) Plus, the cup connector (what the heck is that thing called?) is low so it would work with both a tube-style or strapless sweetheart top dress. You can get this one at Calvin Klein or Nordstrom.
In the case that your dress has a low back or if the material of your dress is thin, I would recommend the Le Mystere Bustier. It is made of nylon and lycra so it can stretch which creates a surprisingly comfortable bustier, while smoothing any unwanted lumps. It is seamless so it cannot be detected under your dress. Also, the cups have underwire which keep the girls securely in place. It doesn't have any padding and the lining is relatively thin, which I liked for the above mentioned reasons. I wore this bustier for over six hours, under a huge strapless ball gown and I felt great. I didn't have to adjust it at all. Also, this bustier comes with removable straps as well, so if you're wearing a one strap gown, or halter you can adjust accordingly.
If your dress is extra fancy you may need to go with this one: the nubra . It is literally two silicone cups attached by a clasp in the center. The cups are adhesive so they stick directly on your chest. This bra is good if your dress has an extremely low back or a plunging neckline (as you can unclasp the two cups). It lifts and helps shape. I've personally had success with this bra. I wore it on a few occasions and once for about five hours (while dancing and sweating profusely) without any problems. You can order it from Lula Lu, which is a great website that specializes in bras for smaller cups sizes, mainly AA-AAA.
Like Andrea said, it is important to be flexible with your bra size when it comes to strapless bras. They can be very tricksy! I almost always go down one band size, just to ensure it will stay up. However, if you aren't careful, going down a band size can create some unwanted lumps. Also, it helps if you can bring the dress with you when trying on bras and definitely bring the bra to any alteration sessions. Lastly, a little love and support goes a long way. So be patient and find something that properly contains or displays your ladies in a way that you're comfortable with.