Well, in all honesty, she does look a bit on the more rotund side to me...and trust me, I'm not one to talk with Fergus weighing 18 lbs (he's a Turkish Van, which is a larger breed, and he's not round at all...he's long, and very sturdy, or maybe that's me in some kind of denial...
Here's a possibility with cats outdoors...neighbors feeding outdoor kitties or offering scraps/treats unbeknownst to you. It happens...and kitties start to gain weight. And I do agree with others, I'd cut out the dry. Wet is better, less carbs (which are the #1 reason of obesity in cats), and more protein.
Ripley and Fergus each get 1/2 can of wet food twice a day...once in the morning and once at night...and that's it. Ripley is 9 lbs, and is at a very good weight. Fergus...well, he's just one of those natural giants...he's got a big build.