I'm sorry you had all these problems, and am really glad you posted about it. It is even better that you have figured out a way to turn her lemons into lemonade as Irma Bombeck would say.
I have learned so much from all the answers and solutions offered. I had never really thought about what to do if there was a lot of slack in a quilt top. I don't pre-wash my fabrics, so am now going to be looking for one of those hand held steamers, just to have on hand. And, I like your minimal free motion quilting. It greatly enhances without making it look like it is too heavy. Great job.