Victoria's Secret Bra Top

I do not know what size this is. I purchased it ages ago from the VS website, it is probably a medium. I cut the size tag because it was itchy and uncomfortable. The color is a gorgeous bright purple. Measurements are in inches. Pit to pit measures approx 15 flat, 18 stretched. Elastic under bust (the elastic that acts as the bottom of the bra section) measures 11 flat, but also stretches to 18. The halter part is 2 long strips of fabric that can be tied however tight you like.