Something to think about since you are only at this point (seeing how you've been steered in the right direction about points), with the shape you have I would piece on the diagonal instead of horizontal rows. Two triangles make the rhombus shape and I would be inclined to chain sew the triangles in twos and the piece diagonal rows, like you would with blocks that are on point. To me, it'd be easier to sew with less distortion.
But that's just my first inclination, have fun however you work it out.