Your quilt looks great but I understand where you're coming from.
When I first started quilting one thing my teacher stressed was measure, measure,measure. May be if you are folding several times before you cut that is causing a problem. Better to measure and mark the quilt before you cut. Saves so much stress and less ripping out.
We are each our own harshest critic. Something my quilting friends & I have discovered is not to judge what we see up close. When one of is not sure the others will hold up the quilt and the owner gets to view it as it will be seen on the bed. A view of the whole quilt not just the block or whatever is causing us to be unhappy.
When it is on the bed that is what we see- the whole quilt.
You have done a fabulous job for your first quilt..