When you SITD, put pressure on both sides of your seam to pull it open as far as it will go and be sure you are sewing on the side of the seam opposite of where you pressed the seam allowance. That way, when you release the pressure, your stitches will truly be in the ditch. And remember, it's not a race. Take your time and you will like the way it turns out much better. Good luck and show us the finished quilt!