Your left side is knotted because either you are struggling with your feminine side or you are having problems with other women in your life. Are you nurturing yourself enough? Do you have enough time to be feminine? Is there a female in your life right now that you resent? Or do you have some general anger and frustrations towards women in general? Do you feel you need to put on a brave and courageous face for others? Do you feel your masculine side has taken over? Perhaps you now judge other women as fickle in some ways?
The shoulder connection links with the liver/gall bladder area. So this is more related to either anger at your self or anger directed towards another female - more than likely repressed, hence the knotted up feelings when we don't get to express what we really feel inside. Our *civilized* society makes expressing anger difficult ... and perhaps you judge loosing your cool to be a poor way of dealing with your frustrations.
The shoulders represent our abilty to carry our experiences forward in life with joy, otherwise, we carry them as a burden and this limits the abilty to feel that life and our experiences are loving and joyous.
As a mum who was single for many years with twin boys, I can resonate with those issues and also used to have very knotted shoulders.