I agree with what everyone has said. Usually we tend to be our own worse critic, and see absolutely EVERY single mistake. It's a mistake, it's not life threatening and most likely if you give to someone, they would never see the "mistake", just know that you gave them a beautiful quilt/wall hanging.
I actually think that you don't have any confidence in what you're making your quilts, but honestly, the more we quilt the better we get, and the fact is that some people seem to be a "natural" at the actual quilting. I'm NOT one of those, even if I had a long arm I don't think a million years of practicing that I would come close to being as good as some of these gals, but don't put yourself down, enjoy your sewing/quilting and you will get better.
If you're having a problem with a certain procedure, post your problem/s and show us pictures and I'm sure that someone will be able to help you through it.
If you enjoy the sewing, enjoy it, quilting is supposed to be FUN not stressful.