Vintage Gunne Sax dress Small Black 1980's-1990's

I'm blown away by this piece. The fit is very very odd however. I can only fit my top half, but my lower cannot fit. Defiantly for small thighs, no stretch in the material. Waist: 13 inches flat Armpit to armpit seam: 15 inches flat Shoulder to hem: 41 inches If I were to give this a number I would give it a size 2, Small or XS I am normally a size M or 4/6 I'm flexible with pricing!