Hi, and congrats on your pregnancy! When I was pregnant (six and four years ago!) I got most of my maternity clothes from JC Penney, either the store or from the catalog. I think they may even have a seperate maternity catalog you can request which has a much larger selection than the maternity dept in the store. They were the only place I could find plus-size maternity clothes, and they have pretty much everything: work, casual, all season, etc, though their casual clothes were much less expensive. Check them out if you haven't already...and good luck!
Laurie