Hi, Someguy!

First of all, do you work with a personal trainer? If no, I'd check your program to reduce possible mistakes. Maybe there's a poor posture or wrong stance involved.
I also know that prior injuries/surgeries cause muscle asymmetry, so if your technique is fine, that could be the reason.

But need to mention, I'm not a professional trainer, so I'd recommend you to ask for some recommendations from your local trainers.