Womens warm romper, grey with silver buckle, NWT, size XL but runs small

This is so cute and heavy for fall/winter. It is NWT but I have not been able to find this brand online so I'm not sure where exactly it's from. Size XL but runs very small, would say it fits more like a medium. I included a measurement of the waist in the photos. I think it might be wool but there is no inside tag so I'm not sure.