Welcome from Ontario, Canada. If you have cut your pieces accurately and sewed good 1/4 inch seams, there are a few things you can try. Iron the top with spray starch and see if that helps. Dampen the quilt top with a spray bottle and block the top out on a clean surface to dry. Use an extra high loft batt to hid the puffy parts when quilting it. If you are able to post a picture of it, someone might be able to offer more specific advice.