This can be a serious problem when working with bias edges. In the future, it is not a good idea to cut scallop edges until a top is quilted. But back to your problem. first of all I would steam the areas that are stretched. This may help to put them back in shape, or at least improve the situation. Your binding should also be cut from bias. When applying bias binding to points, always miter the point, do not stretch the bias to fit.
Unfortunately, not all problems can be fixed after a quilt is quilted. Consider this a learning experience for next time. Try the tips I mentioned and enjoy the quilt. Finished is better than perfect! Each day of life is a learning process, and quilting is the same. Enjoy the process and congratualtions on finishing what sounds like a difficult quilt.
Let us know how this works out for you or if we can offer any more advice.