I have often used this method for baby quilts or a quick table runner: As you did I use QAUG to adhere my quilt top pieces to the batting. Lay this down right side up, with the batting against the table. Lay the backing on top with right sides (or pretty sides) together. Your layers need to be trimmed and squared up so they are the the exact same size. I sew a half inch seam all the way around leaving a 4-6 inch opening. Trim the corners and turn it right sides out. Work the seams and corners to be flat, press and sew all the way around 1/4 inch from the edge to close the opening and stabilize the edges. I usually do at least 2 straight lines of sewing both length and width wise to further stabilize it and you're done!