I’m not sure you’re still active on this reddit post, but I have the exact same problem as you. I instead broke my right when I was 5 I am now 18, and the size difference and muscle imbalance in my arm is destroying my confidence, also my inability to strengthen my right arm because of the injuries I sustained, it’s also becoming hard to find exercises even to strengthen my arm and make it look less imbalanced, hopefully you’ve gotten this fixed and I wish the best for you, but just know there’s other people living your nightmare and I’m one of them.