He is so cute!!! He looks 100% Yorkie, I think its the hair throwing it off for you. It really needs to grow out! Winstin has been here over a month and still goes after my sassy cat. He just wants to play. She puts him in his place if needed (does not hurt him though) When it gets out of hand I put her to bed in our big bathroom. I want her to learn to ignore him. He has learned to bark and stay back enough to wear she can't swat him.
It is funny sometimes. I think once our pups are older the cat thing will get old and they will all be buddies!
I hope you are having a better day today with him . He is a doll. I think you just need time to bond.