Maybe you should re-do the pin basting, making sure to tape the backing down tight onto the table surface? That makes it hard to pin, but will result in a non-baggy backing. Easier solutions would be to spray baste it together, have a longarmmer baste it for you, or use a non-baste frame, the kind with separate rollers for the top and backing. Good luck. You're on a tight time frame. Hope you work well under pressure. I don't.