Heteronormativity does not define sexuality as a whole. Heterosexuality could look like a woman marrying a transexual man. Some cisgendered people may feel this goes against the traditional understanding of what it means to be heterosexual, however, sexuality and gender are not the same discussion.
Differences in ideologies surrounding gender conformity and heteronormativity do not contribute to general labels of sexuality and gender, legally or socially. Each sexuality may be defined by a preference ‘between two genders,’ but remember gender is not sex—one’s gender is an identity. You may argue gender influences sexuality, but they are not exactly one and the same concept. So, to have a fluid identity could, arguably, not automatically mean you are pansexual; all in all, the label comes down to the individual and how they view their fluidity.
