Could you choose another backing, add the batting and new backing? It will make it thick. If you didn’t do too much quilting you could take it apart. I always use batting for that same reason. I didn’t see your first posts though ( felt and fleece?) what kind of felt did you use? I’ve done plenty of quilts with cottons and flannels with fleece backing but the only felt I’ve used was wool felt appliqué. So, I’m curious