I adore your WOW (white on white) print as the sashing and the dark brown as cornerstones. The cornerstones by matching the outer frame of fabric on your blocks will lend a unifying effect and may also form a secondary pattern once the quilt is all done. If you introduce the orange, do so sparingly. The non closeup shots of your leaf fabric that has orange doesn't really show or read orange from a distance. the few orange dots on that fabric tend to not register. Right now your quilt has a very "elegant" and "formal" feel to it with mostly neutrals and only a few colors along with the white sash and brown cornerstones. If I were to introduce that orange I would go no wider than 1" wide inner border. I would be inclined to even narrower on it if I would even use it at all. I think once you get the center part all assembled would be the time to audition and decide if you want to use the orange or maybe just put a narrow brown inner border and the leaf print outer border. This will be a very nice quilt when you are done.