Ok, I finished the boss level! The game is really adorable and I really love the cat sprite and animations :3
The bird level is too easy and you can just stand in front of the house without any movement. I guess enemies should go not only to the centre of the house, but to the other direction too. Also checkpoints for every stage would be great too.
Boss level is a bit hard. In my opinion boss attacks should be a little bit slower.
Anyways, very nice game!