Cat familiar spell? I will say the spell is nicely written for a fluff one. However, a cat will not just show up to you. At first I was thinking it was referring to a spiritual familiar (aka fetch) which would have made more sense to me. A spiritual familiar is one you do create and design. However, it a bit more complex a spell. A pet familiar? Not so much. Those who believe in actual physical pet familiars don't find them by looking. They just kind of show up and pick you.
Always use common sense when looking at spells. And try to study up on what magick and spells actually can do and how they work. Maybe check out www.witchcrafted.org or www.witchschool.com to start that. After some learning, you will be able to spot a realistic spell and even be able to write your own.