Wow that is going to be stunning when you're done! The quilting really enhances your blocks. Can't wait to see it when it's finished.
I know what you mean about the pain even though yours is a much larger quilt. Earlier this year I made a black/white/gray baby quilt that was 4 really big log cabin blocks. I used FMQ and it was impossible to keep the rows even and straight. I kept doing it that way because it needed to be done. But even with the FMQ I had to keep turning it and pushing and pulling it. My shoulders and arms were so sore. And my quilting looked really bad. Yours is beautiful!