When I started machine quilting, a lovely lady at my guild gave me a tip about using thread in shades of gray. She said don't worry just try it and she was right! a light to medium gray looks great and it kind of changes values depending on the fabric it's being stitched on. A pearly light gray would look great on your quilt. If you don't feel like taking out all the stitching right now, you don't have to:) it's ok to put it in the cabinet and move on to something else for a while to ease the frustration and put you in a happy mood.