I think the two colors per block is going to work better for you. One thing I notice is that your greens are all about the same color and value, which means that they are going to look pretty much like the same color all the way around the animal. (Squint and look at your layout and you'll see what I mean.) I think the look of the quilt would be much more interesting if you alternate those greens with some lighter greens or a yellow, or tan... anything that would provide more contrast. Then make the blocks with the darker color in the corners for half of the blocks, and the lighter color in the corners for the other half. That way when you put them together you can have darks next to light and lights next to darks, but no two of the same value side by side. It makes for a much more pleasing look. Good luck!