Don't get too discouraged. I threaten to quit any and all quilting at least a couple of times a year. Sometimes you need to step away from the project, sometimes just abandon it. You can only do your very best. I have been quilting since the mid 70's and to be very honest, no matter how careful I am cutting, sewing, and reading the patterns, I still screw up. It used to drive me crazy. We always our worse critics. Everything you do, you are learning and getting better. It isn't always human error either. Patterns get written incorrectly, fabric stretches, machines pull the fabric....it's actually a wonder that anything comes out right.