What a happy quilt!! It is a pleasure to see! How about doing your border in various lengths of your main colors in strips. No small pieces at all. Then you could finish it with a white border. The color strip border would be your frame and keep your eye looking into the quilt, then if you have more strips left, make the binding a happy colorful binding it would stand out against the white border. I am sure whatever you choose it will still be a beauty!