If you have a Nordstrom's nearby, they are the best for bra sizing. Their bras are expensive, but good quality. They carry a few good brands but not a huge selection for nursing bras. Free shipping both ways if you need to return anything.
For online, Breakout Bras can't be beat for prices, selection and customer service. They have great sizing instructions plus the site owner writes little notes on almost every product page about how the sizing runs and who the bra is good for. You can also live chat with cs if you have questions. No fuss returns also, although you will have to pay return shipping. I ordered a few sizes and sent back what didn't work. They have a huge selection and always have a 10% off code right on the page, plus free shipping over a certain amount I think.
Motherhood Maternity has salespeople who are somewhat knowledgeable and more affordable bras, but I couldn't find a comfortable bra in my size there.
If you are trying on in store, remember that the most common mistake is to get too big of a band and too small of cups. The band should go straight across your back, not be pulled up bu the straps. You should not be spilling out of the top of thr cups. The bad should fit snug on the biggest setting because bras stretch over time and you want to be able to adjust for that.
If you go down a size in the band, you need to go up in the cup for an equivalent cup size.
Last edited by mamaspice; 12-06-2012 at 11:00 AM.