Your quilt is lovely. In order to avoid those waves in the future, do this. Make sure you are pressing with a dry iron. If you must have the bias on the edge, put some foundation on those blocks if they seem to need it.
Measure for you borders from the middle of the quilt from one end to the next. Always pin the middle of the border to the middle of the quilt. Pin both ends and ease in what ever is left, more pins if needed....then press and measure down the middle for the other two sides and do the same. Cut borders on the straight on grain.