Aside from what the others said, try to keep your upper body more still at the canter. You're kind of bouncing on Jinx's back like a sack of potatoes at times, which is understandable since you're just getting back into riding and you need to build up the muscle again. I'm sure that the problem will correct itself in a few more rides once you start gaining back muscle but its just something to think about. Also try not to pump with your upper body as much as it upsets your horse's balance.
I'm loving your leg position, although your stirrups are a tad to far back on your feet. Positioning them on the balls of your feet will help your heels come down more. Try to follow the pony's mouth more with your hands. At the moment your hands are basically in your lap with an inconsistent contact. Move your hands forwards, shorten the reins, and move your hands with his mouth to maintain a steady elastic feel. Lastly, work on counting your strides in (one, two, one, two) and really try to feel your horses rhythm. Don't 2-point until his feet come off the ground. :)
-----In riding horses, we borrow freedom-----