I agree with those who say it is a beautiful quilt. I think the only thing you could have done better would be to get all those loose threads off. I just snip mine. This is not a quilt for a major quilt show. So what's the difference if the corner is not quite square. I "almost" never hand sew the corners of the binding. I've done it twice. The second time my quilt got a blue ribbon and the judge commented that I had done that. But it surely is not necessary in my book.
I agree that the shop may have their underwear in a knot because they were not paid to do the quilting. A kind person would have told you "kindly" how to improve a few things.
You are a beautiful person. I can tell by the way you are answering all these comments. Best wishes to you.