Advancing in yoga is more related to refining than to attaining.  If you want to know if you are advancing in yoga, ask yourself these questions:  Are you gaining greater understanding of your body?  Are you learning how to heal yourself?  Are you learning subtler and different ways of using the poses and how each asana affects the body to produce different results?  Are you gaining an understanding of the energy fields in the body and how these energies flow?  Are you beginning to get some control of your own autonomic nervous system and some of the unconscious processes of the body?  Are you less rigid in your beliefs and less fixed in particular systems and structures?  Are you alive and awake in your practice, constantly questioning and willing to get off your position—figuratively and actually?  Are you questioning, not only of others but of yourself?  Is your mind becoming more open, compassionate, more peaceful?  Growing in these perceptions and capacities provides the necessary ingredients for the evolutionary process of alchemical transformation into radiant health, higher consciousness and wisdom.