It's definitely thin for a female, but is it possible it's male? It's shape reminds me more of my males and also it's behavior. When my males want to breed, that's all they care about, they constantly are moving and wanting to come out and explore but could care less about eating. You'll still want to try and get it to eat because it's still not healthy for males to lose weight but in my experience, it is more common for them to act like what you're describing.