I had the same problem the first time I tried this block. Here's how I broke it down. I used red and blue for the main colors and gray for the background as it shows up better for illustration.
Cut your A's 1/2" bigger than wanted. Save back 1 square of each main color for cutting in 1/2 diagonally to use with the E blocks.
Sew on either side of drawn line shown on B's.
Cut your C's 1 1/4" bigger than wanted. Cut into 4 pieces. Sew these like shown on D. Watch for bias stretching!
Sew main color D's to E triangles.
Now you should be ready to assemble. Good Luck.