I didn't notice this dress online but it jumped out at me at the store.  i sized down to a small as the bust and arm area seemed very loose in  medium.  (36b). it's very comfy and beautiful.  i tried it with  a belt,  but quite honestly  it doesn't need one and it looks so much nicer without one.  not sure about what bra to wear ...likely strapless , or as one person said. .none.