imbalance left vs right

background: I am an avid powerlifter. I developed very bad quadriceps tendinitis in both knees and inflammation in my left shoulder around 3 years ago. Since then things have improved due to working on mobility and stretching but I'm still dealing with lingering issues. I believe there has to be an issue that causes an imbalance in my body because of the difference from my left to my right side.

issues lowerbody:
- left side: pain in knee. tight TFL en QL
- right side: tight hamstring, nagging feeling in I believe piriformis

When I do single leg romanian deadlifts my balance is better on my left side.

issues upperbody:
- left side: impingement in shoulder, bad external rotation
- right side: inflammation in scapula. bad internal rotation. when I put my hand behind my back my shoulder tilts forward, my scapula wings out and inflames

I believe I can summarize it like this:
- bad internal rotation in left hip en right shoulder
- bad external rotation in right hip en left shoulder

Does anyone have an idea of what could cause this?

personal theories:
- I have a slight discrepancy in leg length. I was told it was not substantive enough to cause issues. Maybe it does because I'm over 200 pounds a I work out a lot
- I sleep on my side but not exlusively on one side