Antik Batik cover dress

Purple cover dress with light yellow flower sequences - front of the dress has 4 buttons - dress fits above the knee (see last picture. I’m 5’6) - I’m having a hard time with the sizing.. it says Y8 if I had to give it an American size (lol) it would be xs. In the last picture you can see how it fits me tight in the arms/shoulders (I’m 140) - each side of the dress has 6 inch slits - left should/arm is a little faded from the sun - no stains, holes, nor tears