After you have squared the blocks before sewing them together, and then squared the corners of the sewn-together quiit, measure across the CENTER of the quilt, not the edges, to determine the length of the border. This is how you get the quilt to hang straight. It also makes the borders easier to quilt - you don't get clumps like you seem to be having. The edges may have stretched some in sewing. You can ease the edges or the border a bit to make them come out evenly. You'll find these same directions in most quilt books and on-line directions