70s Striped Floral Shirt Button Front Large Dagger Collar Mod Autumn Blouse XS

Vintage early 70s Andrew St. John double knit mod rugby striped floral button front blouse shirt. Long sleeve with buttoned cuffs. Oversized collar. Fitted silhouette. Very stretchy fabric. A small stain in the back of the sleeve, see last photo. Size marked M, but fits more like an XS. Please review the measurements.