Especially for larger women, for comfort's sake, it's important to wear a proper-fitting bra.
The best place to be measured is at a store that specializes in larger sizes, in both cup and band. However, many stores that cater to larger cups only stock sizes for large bands.
This site has bras that start at a size 28 band and end at a J cup. It's expensive, but can help with issues such as back pain. It also has good tips for finding the best fit: www.figleaves.com
_________________
"I've been really, really anti-social for the past few years, and I'm just starting to get over it, and come out of my shell, and be able to like people again" - D'Arcy Wretzky