What breed of cat is this? (7 lb, not fat, 4-5mos old)?

A Domestic Short Hair (DSH) which means breed unknown and most likely a mixed breed. Unless it came from a breeder with registration papers it is a mixed breed which most cats are.

It is a domestic short hair DSH bi colored also called a Tuxedo cat.

No breed or mix. It's a domestic like over 97% of cats. Do hope you've gotten it altered????

Domestic short hair - color is black and white bicolor. Very cute.