Six Letter Girl Names

Occupational names are hot right now, and Doctor has recently reemerged as an option. It's also an honorific name, a la Bishop, King, and Princess. It's never been popular for boys or girls—Doctor peaked in 1884 after being given to 12 boys—but it received a lot of attention after being banned in New Zealand.

Unella is a fictional name, borne by a Septa in the Game of Thrones series. A pretty sound, but the negative character association might put you off.