Johnny Was J3 Workshop Blue & White Striped Floral Embroidery Button Down Tunic

I am selling a Johnny Was J3 Workshop Blue & White Striped Floral Embroidery long sleeve Button Down Tunic. it is excellent used condition. unfortunately, all the tags have been cut out so I am unsure of the exactly size, my guess is that it is a size medium. please see measurements for more accurate fit detail. the buttons do say J3 Workshop. I tried my best to take a picture but my camera was unable to pick up the detail. measurements (laying flat) armpit to armpit: 23" sleeve length: 18" back of neck to hemline: 29 1/2"