I never have made a QAYG quilt but have an idea but I just can't seem to make it work all the way in my head. What if you cut a strip of batting to lay over the flat part of the back of the blocks where you joined them. It will fill in that area with batting and cover the dark strips that you pressed open. Right? I can't figure out how to attach them but maybe somebody else can? Maybe it means you have to stitch each strip of batting by hand to the dark edges that are pressed open but it might be worth it in the end. Then you can use the fabric you bought for your quilt in the first place.