When you are doing hamstring stretches in yoga class, you might notice that one leg is harder to stretch. That is normal, most people do have one leg longer than the other and you don’t have to be symmetrical: just flexible and strong. Get into the feeling of each leg, and try to find the place where they both are equally stretched and loosened.
In anatomy class I found out the reason one leg is longer is because when we are standing in a 3-D gravitational field, therefore we compress in a spiral. That is the geometry of bipedalism, two lengths in motion in a gravitational field will make a flunctuating spiral. We need that flexibility, and that is one thing that yoga will give us.
If you find the internal balance of the two legs in your yoga practice, and persist with your lengthening and strenghtening exercises, it will help you with the back problems that can be traced to the pelvic bowl.
Just let go of perfect and feel your bones.