I like Dr. Sears, too. Try secondhand stores for Motherwear clothes, too, or their website for the "clearance rack." I make skirts and wear their shirts, or I wear dresses that button at the front with their *extremely practical* undershirts. And I have one winter and one summer church-nursing dress.
Their sizing is funky, unless you're very tall, but you can return everything, no matter what. I bought one dress, when I was nursing Sally ... in Extra Large, it trailed on the ground. In large, the hem was off the ground but the waist was below my hips. In Medium, it was too tight in the chest. I sent them all back, AFTER washing, and got my money back.
One of the reasons I am nervous to nurse in public is because I have read and heard stories of people being harassed for it, even though they are well covered up. Have you ever had anyone approach you for breastfeeding in public? There was a lawsuit filed against Walmart here in Ohio because they asked women to nurse in the restrooms, and walmart one the case here.