Am I being too sensitive?

My fiancé got me a cat for my birthday. She's 6 months old now. Ever since we got her, my fiancés daughter doenst leave the cat alone. Constantly picking it up, taking the cat to her room WHENEVER she wants. Sometimes the cat is sleeping and she just wants to hold her, which I understand but she doenst let the cat rest. The cat sleeps in her room because she's a bit too hyper at night and we sleep in the living room for now (our room, which is the basement, is under construction) I like to leave our cat out until I know I'm going to sleep so she can be out and roam around our house as she pleases. I feel bad when we have to put her in my fiancés room. Tonight she just got the cat and took it to her room. She doenst say anything, doenst let me know she's taking the cat, doenst ask if it's ok. Am I wrong for feeling this way? I mean, she's not mean to her. She's a good animal person and makes sure she's fed and watered. But I just don't like how she thinks she can just take her and lock her in her room. What if I still want my cat out here? A part of me feels I'm being stupid and childish but another part of me feels like that's my cat and nobody should be taking it whenever they feel like it. She's 16 years old by the way.

Update: She spends one week with us, one week with her mother. She's rude, very disrespectful. And I think that has a lot to do with how I feel towards her