I'm a perfectionist, which makes learning a new skill difficult because, just like you're talking about, I just want to rip everything out when I see mistakes. Somewhere in the back of my head I guess I'm certain I'll do it
perfectly one of these times... except that's not how being a newbie works, of course!
I'm still a relative newbie but I watched the Youtube channel The Midnight Quilt Show and her mantra of "'done' is better than 'perfect'" has been a life saver for me! As to your quilt issue, I agree with the previous poster who recommended un-pinning it, trying to spread the extra fabric out where needed, then re-pinning it. A couple tiny bubbles is better than a big one. Or, though this is more difficult, maybe see if you can try folding the extra fabric into a seam to disguise it?