I keep my backing clamped to the table until my many many pins are in place. I make sure it is smooth and straight on the table, snug but not overly so because when it is too tight and you release the clamps your fabric relaxes and can create pleats when you cross sewing lines. I only clamp the backing. The batting and top are smoothed continuously as I pin. Nothing is so maddening as having to takes out tons of stitches. Sorry for you.