So I am stuck. I want to dress up as a modern vampire for a party, but I really am having trouble getting ideas or even where to start. I am a girl and one thing I won't do for this costume is wear a dress.

Hmm. We don't see many female vampires wearing pastels and bouffant hairdos and pink lipstick.
There is sort of a stereotype of tight black clothes and very dark makeup.
How about looking neither male nor female but sort of both, and wearing a fitted man's pin stripe suit with a woman's plain silk blouse? Hair gold on one side, silver on the other. A banker vampire.