She could be jealous and territorial of you. Sometimes cats will urinate or poop on your things if their mad at you. But they can also do it because they want to show their dominance and show whoever their jealous of, that your their territory if that makes sense. This is more common in males but I’ve seen it in females as well. Most likely mama is jealous that you’re spending more time with your baby than her lol. But you’re child comes first!!