You don't need much until you get to the row where you see the purple/white. You cut 4 1/2 in squares and enough to make 1/2 of a few 9patches that are 4 1/2 . Go for it!!
I only use bias binding if edge is scalloped....straight edge=straight cut binding.....but the quilt is gorgeous! I have admired this pattern but too chicken to try it!
This is the same way that I choose my fabrics for my Bargello quilts. It takes days of tweaking before I feel comfortable with the fabrics I have chosen. You made a very stunning quilt !!