It's cute, but I don't think it would be a good choice for an actual baby name. Agree with naming her Katherine (or indeed Kathleen, Katya, Katrina, etc) and calling her Kat for short with Katniss as a nickname. That way she could choose whether she wants to continue going by Katniss or just use Kat, and when she grows up she'd have a full name to go by that wouldn't lend itself to constant cat piss comments.