Slightly better on the left side, but no real difference on the right. To make matters worse, the front turned into an 80's style half-shirt, ending just under my bust. (I'm not entirely surprised by this, as I felt that it hit in the right place at my waist originally.)
I came to the realization that this is a problem I can't seem to solve on my own. I endeavored to seek out a tailor in my area who I could cajole into giving me sewing lessons. I was pleased to discover a sewing studio near my job (what did we do before Google?!) that has open sewing classes on Monday evenings.
After reviewing the dress's bodice, the instructor believed that I am cutting the size appropriate for my bust, but not my my frame. She took my measurements and determined that my high bust (upper chest above my bust) is a scant 32", while my bust is a 34". I've been cutting a size 12 for the 34" bust.
She suggested that I cut a size 8 (on this pattern, a 31.5" bust), but add to the side seam to get my waist size (I had to add about an inch on each side, so I'm probably back to about a size 12 at the waist). After tissue-fitting the pattern, she recommended a full bust adjustment to accommodate a 34" bust. The instructor showed me how to do a FBA; here she had to add a side dart in addition to the previously sole large dart that went from the waist to the bust.
I'd need to refer to an instruction book, but I do think that I could replicate a FBA adjustment again. It was so helpful to see someone execute it.
As to the offending back, the instructor thought that I needed to do a forward should adjustment (apparently I have a bit of a slouch from sitting at a computer all day); she did this by adding about a half inch to the back shoulder seam, and removing that amount from the front shoulder seam. Super easy!
In addition to pinching out a bit of "fabric" on the pattern near the shoulder where it was still gaping (the fold in the picture below), she felt that I needed a rounded back adjustment (the pie-shaped addition).
It was really helpful to actually watch someone cut the pattern to make adjustments. My next step is to lower the front bust dart slightly as it is not hitting at my "apex" (the fullest part of the bust), and then sew this up to see if this fits. I'm hoping these alterations do the trick! They looked right in the tissue fitting, but frankly, I'm slightly wary of the Palmer Pletsch's much-exalted tissue fitting method. Firstly, it only shows one side, and secondly, fabric must hang so much differently than paper. But I'm new, and these are just my impressions! Perhaps I will turn into a convert. Do you have any thoughts (negative points or love stories) about tissue fitting?
When I began sewing, I thought that I could do it on my own. I do feel that sewing is like cooking: if you follow the instructions in a cookbook, you can make a meal. Similiarly, if you follow pattern instructions, you can make a garment. For me, I'm realizing that while I can learn to sew, fitting is something that I just can't seem to grasp by reading it in a book. That's just me. I think that attending this studio will help me to perfect the fit of muslins I plan to make of classic patterns that I'd like to sew in multiples: a Chanel-style jacket, wide-leg pants, the perfect shift dress...