Fabric has a side that stretches and one that doesn't. I try as best I can to always put a stretch side against a non stretch and ease it is if needed. Learned that in sewing clothes. Kept doing it when piecing. Don't over handle it. Seam allowances are very important. Measure each block as it is finished. Make a paper template of what ever the size is supposed to be. Lay it on top of the block. can't see it at all or too big. check the seam allowances. Be very strict about this. Jan