I love your quilt, your colors, the pattern, all of it. I have been doing the same thing, practicing the QAYG technique and had the same problem, getting my sashings lined up. I think it's something that just takes practice. I have found that once I have the first row on, then if I mark the sashing with a ruler, it goes a lot better. Like on your first row of blocks, after you put the bottom sashing on, mark the sashing where the vertical sashing are and then it works better. I still need practice on that too, but my last one came out a lot better than my first.