You should have plenty of fabric, lay the backing down, right side down, then add batting and quilt top. I would tape the backing fabric down to prevent it from shifting, pin well and you should be fine. Another method would be "burping" the quilt, but I don't think I can explain it well enough for you, so you might check on-line. I have seen episodes of Alex Anderson where she has used this method for baby quilts, but there are others I'm sure.