I'm 5'8'', 33-25-34, and I got a small. This costume is beautiful! Its pretty comfy and airy. The dress is made of pretty light but not sheer fabric. It is not structured on the inside but is well fitted. The skirt part of the dress is also lined with a layer of sheer purple, the same fabric as the shawl. The undershirt is sheer and sparkly. It may bunch up across the chest if you move your arms up and down a lot but thats something that just happens with stuff like that so you'll need to keep an eye on it and tug it into place during shoots so that you don't get a line across your chest like I did in some of my photos haha.
The dress is LONG and the slits are high! I'm 5'8'' with a long torso and even then the slits go up so high! You'll have to wear tights and / or high cut undies! Or just black bikini bottoms if you aren't comfortable with high slits. The dress is long too, even in my heels! So you may need tall shoes so you don't trip!
The shawl is nice and very long! A tripping hazard if it drags lol so be careful!
Overall this costume is amazing!!