Lol, I think your quilt looks great. I did this very thing on purpose awhile back when I had some fat quarters and wanted to be able to showcase the fabrics AND make it big enough for a baby quilt..... I would undo the two side borders just enough to trim the bottom straight across with the narrowest white on the left(it would remove all of the tan sashing, then add a tan bottom border the same width as your other borders. Voila!
