I have a spinal injury as well, and am still recovering from surgery. Your concerns are legitimate concerns. I do not take my two adult dogs out at all, my DH walks them. The two pups are much easier, they do not pull and are perfectly okay with me walking them in my chair.
A muzzle is never a bad thing if introduced properly. It will allow you some peace of mind, which will in turn relax you, and allow your dog to feel that relaxation.
Do you struggle to keep hold of the leash? I know with me, the spinal injury caused some pretty serious nerve damage that makes it to where I cannot feel my hands and feet, which in turn means I cannot feel the amount of pressure I am applying to the leash.
Before my injury, I had a 4yr old rescue who was reactive on leash and tried to go after other dogs. I worked one on one on and off over a year to nip this problem. She now lives with 3 other dogs with no issues, and she also loves cats! Our GSD/Husky doesn’t, and wants to put them in his belly, so for the sake of the cats, they were rehomed to my niece.
I personally think you’re heading in the right direction with working on these behaviors with a professional. Search a thread called “this may be an odd request.” I was assisting a retired veteran with his Shiloh Shepherd because he was too weak to walk him, and @David Winners
posted some great links for assistance programs for dogs and vets that may be able to assist long term.