Is my cat starting to become overweight?

I have a one year old, indoor DSH. I feed her Wellness grain free wet food, plus a little dry food at nighttime. I give her one can of the wet food a day and probably a half a cup of dry food at night. I weighed her today and she's 10 pounds. She has a little area that hangs down on her stomach that she got after she was spayed, but she recently started getting a little saggy by her front legs. I play with her all the time and she has tons of toys and things to do. Is 10 pounds normal for her age or should I be trying to get her to be more active? (When me and my boyfriend move into our new apartment she'll have more room to run around and we were talking about adopting another cat for her to have a friend.)