If you are basting with straight pins, yikes, that can really hurt. Usually when I pin (using safety pins 1"), I pin a little bigger than my fist or about every 4 or 5 inches. I use Hobbs cotton batting and the quilt tends not to shift. Are you doing FMQ or straight stitching?? You do need support for your quilt on your left side and behind the machine to make sure the weight of the quilt doesn't tug. Most of my quilting life, I have had two Bernina to quilt on and I still have both of them.