So I tried another pouch. This one only has interfacing on the lining and was made from 6x6 inch squares. I also only covered the top half of the zipper.
It still isn't perfect. I think next I will try:
- 5x5 inch squares (I think it is cuter smaller)
- interfacing on both side again (it kept its shape better)
- no zipper covering on either end (too bulky)
- no interfacing in the key ring loop so it is not as stiff