I had that problem with a quilt a while back. Started ripping every thing out then just got fed up with it and cut most of it apart. You really have to be careful with the backing while you are quilting to avoid puckers. Puckering on the front could be from to thick a batting or to much pressure on the foot. Set it aside for a while, take a break from it and go back to it later. Maybe in the mean time you can work on one of your other projects.