The layout of this block is a standard 3 x 3 so to get a 12" finished block your unit sizes are too large. Surprised that some of them turned out ok. Here is a tute that may help you. Make it with scraps to test it and insure you are getting a consistent block first. Then remake it with your actual fabric.
http://www.quilt-lovers-guide.com/ju...#axzz5yfaZ7Db7
Just found another that gives the measurements for 3 different sizes and better instructions for sewing with pics.
https://www.learntoapplique.com/home...r-quilt-block/