This is just a lovely dress, beautifully made, and I am delighted by the pockets.
The corset detail is only anchored on the sides of the dress, which makes it adjust nicely to your body dimensions.
Sizing details: I wear a HAH Large for panties and bras. Seeing the reviews, I was concerned about it being too tight in the waist (my waist fluctuates between 29-31”) so I got a size Large, but I really should have gotten a Medium. The waist is actually about an inch too roomy for me, and the corset detail fits ok if I pull it as tight as possible and let it bunch up (if I had a size M, I would pull it tighter). The bodice is a bit too roomy overall, and the arms aren’t quite tight enough to stay up if I push them up. I have short arms, and the sleeves hit an inch above my wrist bone. My underbust measurement is about the same as my waist, 30”, I have narrow, sloping shoulders, a short waist, and high hips. My breasts are 32H (one is bigger than the other and you can kind of tell because the lace detail sits differently on it). The dress is still lovely, and I might try to tailor it to fit better. My advice - if your body shape is like mine and you want a tighter fit, go for the Medium!