There are many experts here, I am not one, but I find using the walking foot for the straight stitching and the darning foot (which does not sit like your regular foot) for FMQ designs, ie. curves, loops, etc. Learning to use your hands and foot take lots of practice to get the stitches even, and well worth the effort. Try working on a practice piece of fabric layered with batting and backing fabric. Good Luck! Your quilt is lovely.