my dearly departed Monego used to stay in one spot for long periods. We'd leave the house for a few hours just to find him in the same spot when we got home. I don't know if he never moved, or he just got up and stretched, then laid back down in the same position. He was always reluctant to move from wherever he was settled too. If he was curled up in a shoebox we could carry the box all over the house without him trying to jump out. He didn't poo every day either but he did pee regularly. The vet kept telling me for years that "some cats just don't poop a lot", but this is what eventually led to his early demise. Please have the vet check to make sure she is not constipated and slooooowly backing up, due to megacolon or something similar.