If she asks in the hallway, I'll say "good", "fine", "okay", or "wonderful" sarcastically. I've already asked her whether it's a serious question or small talk in the hallway, and she said small talk. And she does know that if I say "wonderful" it's sarcastic (because I'll probably never feel wonderful).

When we get in the room, I'll say the truth either vague or descriptively. Might be something simple as "I'm struggling" or "not good". Or it could lead directly into a specific problem.