Who am I? - Poetic Puzzle | Forum

I am attached to you but can be ahead or behind you
I can of same size, toller, shorter, thinner or fatter than you
I talk when you talk but no one can hear me
I walk when you walk, I stop when you stop and also run with you
I dance when you dance, I limp when you limp
I smile when you smile, you weep I weep too
I change my dress when you change yours
I am you but I have no hunger or thist
I am yours and can be of any shape or form you shape me to be
I am your silent partner but you seem to ignore me
So, conditions are not right I vanish too