ASOS wrap tux midi dress size 12

I bought this dress on posh but it didn’t fit. It was sold as vintage but the material tag had a QR code so I’m not sure the dress is vintage. It is very classy. 56% linen and 44% viscose. One side wraps behind the other and has a button closure. The buttons on the front make the dress. 45” in length. Pit2pit is 20.5 “ with a little bit of stretch. In excellent shape. Very lightweight.