It might sound weird but i think my cat is upset, or in a mood with me?

My cat Milly has just turned one and before we started letting her out all the time (we had to keep her in for four months after she had an operation) she was happy and cheeky and playful. Now, she is out literally all the time and when she comes back, she eats and goes to bed. We're not in half the time either so she doesn't get played with as much any more and I got really angry with her because she keeps bringing in alive and dead birds from the garden. What can I do and what do you think is wrong with my cat??