Im always more observant of the horse rather than the rider, and something that stuck out to me like a sore thumb was how he wasn't stepping into his trot. Usually when a horse trots, the back hoof fits in the hoofprint that the front hoof made. His back end isnt engaged, meaning he isnt moving into his full stride. He is also strung out, which'll make the strides less efficient =)
Anyways, thats my two bits =) You're braver than me, if i had a cast i dont think id ride! Kudos! And its awesome that you're back in the saddle after all that bad experience you had with the car. All in all, after that long of a gap in riding, i think you're doing very well =)
As someone else suggested, it may be easier on your body if you rode a gaited horse =) Out here, when people hit the 65 year mark they trade in their trotters for walkers, lol!
Again, i admire ya for getting back in the saddle!