You are right it is a catch "22", you do what you can, that is all you can do, it is good enough.
Please see an OS or a Physiatrist about your "nerve" pain to determine where it is coming from so it can be addressed.
Think about floor program for exercise, pilates comes to mind.
I am sorry you are having problems with your knee, you have enough to deal with otherwise.
Wishing you all the best,