Lesbian, man, woman...what?

I find myself stuck on the idea of trying to figure out Callie's/Cal's gender and sexual orientation. I've been having a hard time trying to figure out how to think about Cal without worrying so much about how he was raised as a girl and is now a man. Despite the fact that I knew that Cal was intersexed from the beginning of the book, I don't believe that I questioned Cal's gender until the moment that the book started to question it. Before this journey into Cal's sex and gender started taking place, I was under the impression that Callie was a young girl who might possibly be attracted to other women. Starting with her first kiss with the girl next door to her obsession to her best friend's body made me think that Callie could be a lesbian. 

I don't feel comfortable trying to 'figure out' Cal's sex, gender, or sexual orientation or his reasoning behind them. Cal was aware of his attraction to women before visiting the doctor, but did he question his gender? Does this matter? Why does this book that is about so much (history, Greek family, gender roles, immigration etc.) focus on Cal's intersexuality and why does it have to conclude with a definite gender. I feel that Cal was forced to decide on his gender. I think that Middlesex is a great example of the forcing of individuals into categories, whether it be gender, sex, sexual orientation etc.