Although Pandoren mentioned this, I think 'agender' is the closest match to the term that you described. An agender person identifies as neither male nor female, they feel outside of the 'binary system' so to speak (with male at one end and female at the other.) I am also a biologically female agender. Basically, I just dress what I feel like: sometimes I wear ties and compression shirts, other times I dress like a girl. I have an androgynous haircut. My advice would be to not undergo a sex change: your biological sex does not have to dictate your self-expression. Just be yourself and don't feel the need to conform to society in terms of your gender matching up with your biological sex. Good luck!