Black and white is hard on the eye to work on, that is for sure. Even though it is stunning, the process is pretty hard on you. Maybe it is this that is throwing you off?
If you think that the sashings will bring it into line, I would say use those.
But, if you really don't like something, Be Brave and take it apart and fix it. Fabric is so dang expensive! I have had to do this before, and trust me, it isn't easy to make yourself call uncle and do it. But it is very satisfying when it is fixed and finished the way you imagined.