If your left leg is short is from tight musculature that is something you can address yourself.
There are several episodes that address tight hips.
Sounds like this is where you will see the biggest change so address this first.
Start with these:
Super Sumo Groin Mob
Episode 328: Better Surfing MWod & Protecting Your Back From Over Extension
Episode 91: Mobilize In the Position of Death by Chair
Episdoe 23: Runner’s Legs
The spinal erector on the left is over developed because it is making a compensation for the difference in length within the system. Your left hip is making a compensation in position to create slack for you to get to the bottom position in a squat.
The pinching on your right side could be caused by the imbalances on the left side. You are not able to create the needed torque on the left side because of the compensation in position with your sagging left hip.