It is so encouraging that your symptoms have abated following the PB. Do you live in an area that has access to a Pilates studio? Although it's not cheap, working out on a reformer would be a good and gentle way to increase your range of motion and start building strength in your feet, legs, core, and arms. I think you could modify things to minimize stress on your hands. A good Pilates instructor can also help personalize some exercises for you to do when you're not in the studio. Another option is to try to get a referral to a physical therapist to help you get started in weight bearing exercises safely. Maybe I am sounding too cautious; it's probably because I don't know more than the basics about RA.
One more thing to keep in mind is that as you continue to improve and lessen the inflammation, you will begin to do more naturally without being aware of it. One day you may notice yourself standing up from a deep squat and your knees don't feel a thing! I have read that kind of andecdote more than once on this forum.
Anyway, keep up the good work and let us know how you progress.
P.S. I agree with the suggestion on swimming/water exercise--that's a great idea.
I'm a quitter...but I'm back now.