I was going to say Tree of Life (totally my favourite ever store), but you already went there...can you add elastic yourself? Or have a friend with a sewing machine to do it for you (or seek out a handy BBer) - adding elastic isn't too tricky.

I got my favourite pregnancy ones from Target (they could be dresses or skirts), and Myer (the elastic was about 30cm of shirred elastic, so there was no digging at all, brilliant). Just keep an eye out, and get others to keep an eye out. xo

Have you found maxi dresses work or is the top half of those a problem?