New sleeve
I drafted up a new sleeve with a much shallower sleevehead. And it fits so much better! There isn't any more pulling and I can move my arm around, both forward and up! It has a little bit of wrinkling in the front of the arm, which was bothering me. But upon looking at pictures of people who made up the Past Patterns gown (which has a similar pattern construction to mine) and portraits from the era, that front wrinkle just seems to be a thing. The back has just the right kind of wrinkling also. So I am very happy with this new sleeve and am about to cut it out in the real fabric. :D
These 1803 portraits show the same wrinkling/creasing at the front of the arm by the armpit:
These 1803 portraits show the same wrinkling/creasing at the front of the arm by the armpit: