Try to relax while you are doing this. As a retired teacher, I remember worrying when it was my turn to do the hallway bulletin board outside the principal's office the first year I taught in that building. Then, one of the other teachers reminded me that everyone would be looking at the children's work more that at how perfectly I designed the setting. That will be true for the quilt. First students and parents will look for their work then look at the whole thing.
I think once it is hung you will be able to see the timeless beauty of children's art work. I hope you start to feel good about this work. My thoughts are with you.