M.P.
My favorite brand is Wacoal. I'm not pregnant but I also have difficulty finding comfortable bras. Finally, I decided to spend the money and went to Nordstrom's. The clerk fitted me with a Wacoal after trying other brands and it is still comfortable. The clerks at Nordstrom's are trained on how to fit a bra. Wacoal is one of the more expensive brands but it was worth it.
Once they do fit you, you may be able to find discontinued styles at Marshall's, Ross or another discount store. Unfortunately I've not seen anything like the Wacoal that I bought but I did find a couple of other similar styles that worked.
I'm ready for new bras and am going to buy them all at Nordstrom's. The hunt for a less expensive one just wasn't worth it. I probably spent nearly as much on the ones that didn't work.