Vintage Two Potato Laguna Beach 70s Mumu Dress

This is an absolutely gorgeous warm purple. Pull over, no zipper or buttons. The inside label is missing, but I looked up similar Two Potato dresses and they are all 100% cotton. The size label is missing as well. My guess is it’s a size S, but might also fit M. Please read measurements. Hand wash warm separately. Vintage, in perfect condition, no flaws. Measurements (laid flat): Length 43”, shoulder to shoulder 12.5”, underarm to underarm 18”