Karen!
Do NOT give up!
The first thing that I can almost always assume when I hear discouragement in someone's post ...
you are being too hard on yourself.
Why are you ripping the top out?
And, something else (as one hard learner to another).
FORGET RIPPING OUT for at least ONE project.
It is my experience that when someone makes a mistake on an operation, they will immediately stop ... fix the mistake, pick up the next block (feeling like a jerk and worst, stupid), make another mistake, stop, fix the second mistake .... it is a most defeating activity.
My suggestion:
Make yourself absolutely sew twelve seams WITHOUT stopping, without fixing, without doing anything but this:
when you realize you just made a mistake, pick up the next piece and try not to make that mistake on the next one.
and do that twelve times (I like that number <g> if you want to work on five, then fine ... my cattle learn an operation/habit/direction if I do it three times in a row ... don't know if that translates to the human brain, but I digress <g>)
If you keep stopping and fixing something as SOON as you think you did something wrong, you are teaching your brain to stop every time, every few stitches ... if you drove a car, like you are trying to put a quilt block together, you would still be starting your driver's license test ...
When I am teaching others, I encourage them to sew a straight seam consistently .... that is the only thing you have to know to make a fine looking quilt.
Now, that I have given you my best big sister chat <g>
what are you trying to accomplish?
We can help you! I know we can!