Halter style dress with smocking at waist

Size tag is missing from this dress. (Unless I’m Overlooking it- but there are no spots that have been cut out where tag would have been. It’s going to either a Medium or Large. I’d lean more toward Medium, but see measurements below. Rough measurements- Armpit to armpit- 15 inches (with stretch) Length- 37 inches. Color is cream with a light blue detail/stitching. Waist is smocked. Halter with a peephole front. Fully lined. 100% Cotton.