Need help with my results

Hello, I posted this in a group but no comments so far so maybe someone here can help.

Ok slightly odd situation but bare with me.

I have done p90x twice before but always quit in the first recovery week, by that point I lose motivation but i have shed enough weight that I feel ok about giving up (naughty me, I know)

Anyway 2 years ago I had an accident that severed the anterier ligament in my elbow and required reconstructive surgery, I was shelved from exercise and had only one arm meaning I couldn't prepare food as well as I was used to. as a result I got fat and lazy.

So I have started again currently in week 7, it has been tricky with my elbow not being 100% ( and it never will be) but i've been managing or so I thought, during side stretches I find that when I lean to the left I get a terrible uncomfortable sensation in my side which makes me think that I have developed posture problems from my arm condition as I have tried to keep my left side from doing a lot of work.

I then did measurements of my biceps and my right arm is half an inch bigger than the left. That arm is the first to give out when weight training.

Looking into the mirror yesterday I noticed that my left side has a slouch and my right peck is more defined than the left which leads me to think that my push ups have been performed incorrectly and that my right side has been doing a lot of the work.

Can anyone suggest a way that my left can catch up without me having to start over and still reach my goal for my wedding next month?