arm size/strength disparity

Bit of weird one this but here goes.
I've been training off and on for about 14 years.
I started at a bw of about 185 pounds when I was about 19 yrs.
I've been as heavy as almost 300 pounds (both in and out of shape).
Well currently I'm around 250 and look like shite. My waist has gone out further than my chest I think, my legs are all but toothpicks and basically because of a very recent surgery to my right arm I am unable to train anything but my left arm and anything else that can be done via one dumbell. I can't use my right arm at all (and of course I'm right handed as well).
Well - I have managed to do about 5 left arm training sessions over the last two weeks in an effort to stem my muscle wastage.
In an effort to pick up the motivation etc I decided I would measure my arms realising of course my right is alot smaller now.
Well it turns out I've lost almost 4 inches on the right (remember I can't flex the muscles even slightly yet) and my left has grown about an inch since I measured it about 3 weeks ago.
Yes you guessed it - i have about a 5 inch disparity.
Question is - how much further do I go. I would guess I won't be fully functiional with the right for at least maybe another year.
I am going to start some serious cardio to drop the fat and discipline the old diet (getting on in years now and the fat is alot harder to shift?
But my worry is that maybe once I can resume full training I will end up with such a huge strength and size gap that it maybe detrimental to future training and potential growth.
Or am I just worrying about nothing?
Cheers for some sound advice.