Welcome, hun! No fear, use your fabric. Strip it up! The shrinkage, well, IMHO, it's great to get that out of the way before you start sewing. (I do love the look of the crinkled quilts, tho-I just worry about bleeding.) If you start with a (real) jelly roll, you will most likely have shrinkage at some point, either in pre-wash or after-wash. Not a thing wrong with 42 1/2 inches WOF.