long lady in a black dress Ailaoyou Pleated for Women Crew Neck Long-Sleeved Dress Fashion Solid Color Slim-fit Wrap-Around Dress Evening Party Cocktail Maxi Dress (6712 Black,S) : Clothing, Shoes & Jewelry Size:6-12 months Timeless Monochrome Silk Dress Details Sculpting stretch fabric ONE romper

long lady in a black dress Ailaoyou Pleated for Women Crew Neck Long-Sleeved Dress Fashion Solid Color Slim-fit Wrap-Around Dress Evening Party Cocktail Maxi Dress (6712 Black,S) : Clothing, Shoes & Jewelry Size:6-12 months Timeless Monochrome Silk Dress Details Sculpting stretch fabric ONE romper

Timeless Monochrome Silk Dress

A V-neck can make your upper body look longer

ONE romper

Size:6-12 months

The only other thing I could suggest is getting one of the Darkness models which you could use as a basis for designing a costume

Details Sculpting stretch fabric that contours the body Romantic lace panel inserts along the sides Ruched bust with delicate lace trim Adjustable spaghetti straps Floor