I think I would add on a small solid border followed by one made of the same size squares in the sashing and then add a final border on. I would probably use the same color for both borders so the squares would really pop. I would use a solid color that really speaks to you. I would probably tend to go lighter and brighter with that color so the whole quilt will be lighter and brighter rather than too dark. You did a good job on your scrappy!