I think cutting corner-to-corner doesn't work because only the yellow triangles line up with each other. The other two fabrics don't "hang" together because they are alternating squares and triangles. I actually think the fabric selection is fine; it is the cutting corner-to-corner that is the problem.
Here's an alternative way to cut:
http://afewscraps.blogspot.com/2011/...ine-patch.html
Edit: Just saw the more recent photo you posted. Seems to me the secondary design is consistently disrupted, making the design discontinuous. I do like the colors better, but then I am always partial to blues!