Ivory corset blouse with puff sleeves and button detailing

I’m tagging this as Reformation although it doesn’t have a brand tag anymore so I’m unsure. The material feels like a cotton blend, but the tag says 100% poly. The button detailing is so darling and romantic! The sleeves are puffed and also have matching buttons to fasten them. You can unhook the sleeve buttons to open the cuff and roll the sleeves. The tag says medium but I’m tagging it as a small because it runs small. There is some piling in the underarm and around the cuffs. See photos!