I've had many dreams like this too. They used to scare me, prior to coming to terms with who I am. The feeling of 'rightness', not really noticing a difference despite the extreme difference in physical appearance, the
desire alone was enough to make me go mad. Now I enjoy them, a freedom from reality and a chance to be myself.

I'm not saying you're a trans* per se, yet. Only you can truly say if you are. And I agree with @Cindi Jones. Dreams are strong messages from your subconscious. Are you having problems at home? Feeling oppressed and unable to take control? Typically women feel 'weaker' to men because they hold more power than the female sex. Are you having boy/girlfriend problems? Often times people find that strong symbols are a manifestation of emotions or problems one is having in real life. Reoccurring dreams usually mean the issue has not been resolved and the brain is still fighting itself to make sense of the dilemma.
I wish you the best of luck