I agree with Up North - divide the white triangle in half to avoid the "Y" seam. You can then work it out as a paper pieced pattern easily. The green triangle is piece #1, white is #2 and the red or cream (depending which side you are working on) is #3. Then join the two units together to make the points of the star. (Make 4 of these blocks). The other blocks are squares. Wish I could draw this out for you, but I have no clue as to how to do it on the computer, sorry. Hope my explanation is clear.
Anita