A teacher once told us that even being off 1 thread across a quilt with many seams, can distort your finished product several inches. Might be a good idea to work on accurate cutting first, then work to have all 1/4" seams. One half inch seam is waaaay too off to even try to work with! And...some fabric stretches, also, so be aware of that. Try using a good spray product to set your fabric, that might help,too! If given to charities, people who need the warmth don't care about those things. Nothing ever has to be wasted!