What type of batting did you use? Most battings advise how close your quilting design needs to be so that when the quilt is washed the batting doesn't migrate into a lump between the stitching. Your quilt is lovely so far, and if you have a walking foot, stitch nice & slowly allowing the foot to take the 3 layers of the quilt through without puckering. Because you have already done some quilting to stabilize the blocks, I don't think I would choose stitching that butted up to it. I would probably go around the inside blocks, and yes that does make for ALOT of twisting & turning, but hopefully would keep the back from puckering.