Darth, I don't know if you're in a position to consult a fitness trainer with experience in rehabilitation, but I would highly recommend it.
My husband has spinal stenosis. He has been working out with a fitness trainer doing weight work, and has been seeing great results. A lot of the work has been modifying standard exercises to provide additional back support or less back strain.
For example: planks are done with his hands resting on a raised platform (similar to an aerobics step with about 5 or 6 risers under it). Squats are modified, as are presses. Sometimes the trainer does direct rehabilitative manipulation. Step-ups instead of lunges.
All of his exercises have been customized for my husband's injuries and fitness level. He was evaluated before he began these workouts to identify the modifications. I think that you might need a similar approach, with a program customized for you.
Congratulations on your weight loss. That's a great achievement.