I've seen flannels at all the majors... I bought a dozen and a half, but TBH I didn't use them much - I found them still very bulky. When I did use cloth (I mostly used sposies ) I ended up cutting terry flats in half and sewing a hem down the cut side. They were less bulky and I find terry more absorbent than flannels, even at half-thickness. I put a fluffy cover over the top.

Honestly you are changing them so frequently when they are little that they don't have time to leak, especially if you are b/feeding.
I agree - that's what I found with the half-size terrys.