Suggestions Wanted: alt dress for cocktail party

So I’m supposed to be going to a birthday that’s themed as a cocktail party but the host wants floor length formal dresses (which doesn’t fit my understanding of cocktail but that’s another story). My problem is I am an alt girlie so trying to find something that first my aesthetic (and has my size in stock) is proving difficult. Does anyone have any suggestions for brands or websites to check out?? minus the regular berserk, Dangerfield etc. I don’t have time to get the dress shipped internationally otherwise I would look at brands like disturbia too.

The party is about 2 weeks away so I need to get something ordered soon 💀