Star Wars: The Clone Wars 4x13-14

Corey Burton, the voice of Dooku also voices Cad Bane, which surprised me when I first found out but in hindsight it makes sense, both those characters have a certain way with their voice, even if Cad's has that electronic filter on it.

Ahsoka was 14 at the start of the clone war, we are about a year and a half to two years into the war so she is now 15-16. Her lekku will grow longer like Shaak-Ti’s as she gets older.