If I remember it correctly, there is a large applique shield in the center. In my opinion, that is the focal point of the quilt (along the triangles in the corners), and I would want enough contrast on it to draw the eye to it. The blocks you have shown us here are part of the background of the shield and therefore do not need to stand out. In other words, what you have done so far is great!
Again, sincere thanks to an American hero!