First off.. LOVE your quilt.
Have you considered going with a color thread that's kind of "out there"? Like maybe yellow? Or a variegated thread?

Would you believe the only variegated thread I could find "hereabouts" was predominantly greens. A couple of years ago there were heaps of variations available but for some reason at the moment the stores here aren't stocking much variety. To be fair, I'm sure they would get some in for me if I asked. Oh dear, and this is only chevron quilt number 1...I have 2 more to make for grandchildren....sigh....where's that "How to do Macrame" book?:D:(

you may not want to wait to mail order thread, but MSQC and Fabric.com both have variegated thread. I found some nice variegated thread on Amazon as well. If you are an Amazon Prime member you will have it in two days....but King Tut is my favorite
http://smile.amazon.com/YLI-Corporat...n%3A8048904011

https://www.fabric.com/buy/0288628/s...-500yds-mirage

https://www.missouriquiltco.com/shop/browse?q=king+tut

Do the white thread in the white and the grey in the blue. I did exactly that in my chevron quilt and it looked great.
the coloured was child fabric so since it was for a boy I used blue thread.