Have you considered buying her a treat ball? You can put a measured amount from breakfast or supper, a few kibble at a time, and let her walk around and push the ball. It will provide some gentle steps and she can go as fast or slow as she likes. More steps in her day. Her joints may be aching from the weight and her age.
Would you take her measurements, around her waist and chest, and mark it on the calendar? We'd love to follow her progress, and enjoy the transformation with you. Photos too of course!
Engli getting her breakfast..