I lengthened the waist by an inch, then pinched that entire inch out at the center back. Now I'm left with a subtle indentation. The seam no longer matches up with the fold. I read somewhere that I could just straighten the line back out and it would work out fine. Not true! I did this and ended up with a cowl above my tush. So in the end, I decided to cut two pieces for the back to maintain the fit. I also ended up taking in 1.25" towards the top of the seam to account for my rounded shoulders. Otherwise there's a lot of gaping.
What are your thoughts? Is the gigantic pool of fabric that will occur due to my swayback really acceptable? Is the center seam worse? Maybe I've over-fitted the dress? Is it supposed to be loose enough to hide my bum AND poor posture??
*Edited to add the answer to my own question.*
Not a back seam in sight. It seems that blousons and details like this are ways of getting around it. BLARGH.