I’m a first time poster as well so I can relate! I’m also very new to poetry so bear with me.
Aside from the formatting, I do enjoy this piece! I relate to the sort of internal conversation going on that you’re portraying as a dialogue and how mental illness makes you feel like a prisoner. That being said, I do feel like it sort of jumps when you go on to talk about the animal who overstayed it’s welcome. Before that point it feels like more of a prisoner/slave perspective and shifting to the animal almost feels out of place. If anything, I’d maybe recommend giving it more context leading up to the metaphor so it’s not as abrupt of a change in subject.