I would try using your soft background (yellow?). Take your blocks down (you have a photo to be able to get everyone back into position) and put what you have of the background fabric and see if you like what that looks like. It will have a look of floating the blocks. This is where you can play with what width you want between the blocks. I personally can't see using any of your other colors since they are so bright. You could use one of those brights for the binding. Good Luck. Beautiful blocks!