I followed Sew Much Ado's Nursing Cover tutorial. Abby suggested using home decor weight fabric. I agree, it gives the cover more stability. Having used a similar apron for Dolly 3 years ago, I had wished mine was a bit more substantial. I did change a few things.
The "D" rings I purchased were smaller...1" wide. So, I shrank the straps down to 4" wide, and then folded them like bias tape. This made them a bit bulky, and I had to improvise attaching the ring side of the neck strap. I added two pockets in the bottom corners made of flannel. Just cut a 6 inch square of fabric, fold in half and tuck inside the hem before you sew it. Perfect for tucking in a binky or wiping a bit of drool. I also pulled out my double needle and added a little turquoise stitching at the top. It gave the seam with straps and boning a little stability, and added a little flair.