Drumroll please...

I think I may have found the answer to my bra problems:

The 100-way bra. With the low-back option, and the clear strap between cups, you can either wear it strapless (which may not stay up on the bigger breasted women) or you can attach the regular over the shoulder straps, and lengthen them to reach the lower back strap. It's $50 and only sold at victoriassecret.com. I think I'm going to order it. My dress should be finished this week (yay!) and then if it doesn't work, I can always return it (or keep it for other usage).