Jessica McClintock Gunne Sax 1980s party prom dress

Jessica McClintock Gunne Sax 1980s party prom dress black gold velvet Size 0/2 The tag says it is size 3/4 but it is really more like a size 0. I used to be a size 2 and it barely fit then and was really tight. I’m now more of a size 4 and it doesn’t fit at all, cannot get the zipper all the way up.