Just got this today and it's gorgeous! I'm a size 12 in tops (34B) and the Small fits me just fine. A word of warning though.... there is a ZIP on the side you're supposed to undo before HEEEAAVING the beaded bit over your boobs, trying to breathe them in (lol!) and cursing manufacturers and their stew-pid small sizes!
So yeah... undo the zip first, you should be fine ;ox