I believe your little cutie is a blue Swedish. Yes some are black but that has different coloring a then the blue Swedish. A black one has black in the areas that are gray on yours. The head hasn't complete have all its color because it looks like it looks male so it will have a black head. The brown ones are kinda like a buff with a brown head.
PS if u need help sexing, voice sexing is the best way to go
Here's a link, this site helped me find out which is which http://www.majesticwaterfowl.org/artquacks.htm
Or wait until around 6 months old and males have curly feathers on their tail feathers.