It sounds like you have enough of the binding fabric to fix the problems.
-- I would carefully take the binding off of the quilt -- try not to stretch it out of shape..
--I would wash and dry any leftover binding fabric so I would have the extra to make things right.
--I would iron the binding I took off flat and starch it well -- ditto the extra washed fabric.
-- I would cut a strip at least 12" long from the extra fabric and attach it to the binding I took off the quilt
-- I would then attach the binding to the quilt again.
If this sounds like a been there/done that you are right -- my Dad used to say that I learned my best lessons in the school of hard knocks (and I certainly try to learn from all my mistakes). Sigh -- I just wish I ran out of mistakes.