I basted together the muslin pieces for the Simplicity blouse. Initially, I had traced a size 22 with extra (lots of extra!) alloted for the side seams. The additional amount was unnecessary. In fact, it was too wide/large overall, especially in the shoulders. I don't get it. When I had tried the size 22 pattern pieces on the dress form it was a reasonable fit. Also, when compared, the size 22 blouse pieces were not that different from my Bernina My Label shirt pattern pieces.
I cut the pattern pieces down to a size 20, except for the side seams which were left at size 22 and made another muslin. This one is much better. From the original pattern, two inches were added to the hem and the sleeves were shortened by one inch. I also raised the center front neckline an inch and a half. I used a French curve to redraw the neckline and modified the front facing to match.
Anyway, I was able to move freely when I tried this one on. It wasn't too tight or too big. I am going to sew it up!
This is the fabric I chose, a hand washable cotton/silk blend. I bought the pearl buttons from Benno's Buttons.