Is it that you feel that your father might not have left if you had been a boy?
Or that you identified with your father rather than your mother?

Psychologists distinguish between:

1) Sexual identity
2) Gender identity
3) Sexual preference

We are used to thinking that sexual identity and gender identity will co-incide (be either male or female but not both) and that sexual preference will be for the opposite sex / gender.

These things can come apart, though. For example... People with sexual identity disorder believe that they are really of the other sex. This can happen sometimes due to inter-sex disorders (e.g., xxxy genotype) or botched circumscisions where xy (male) is raised xx (female) and so on.

People can be happy with their genotypic / phenotypic sex - but identify most strongly with the opposite gender. So... Some men like to dress as female etc even though they are happy with their sex and don't wish to have a sex change.

Sexual preference is different again. A person can have sex identity and gender identity that is in line and in accordance with their genotype / phenotype. And have sexual preference that is strongly homosexual, strongly heterosexual, mildly homosexual, moderately heterosexual, no preference (bi-sexual) etc.

People still tend to run those together...

I'm fairly heterosexual... I'm happy enough with my sex identity (I know I'm genotypically / phenotypically female and I'm happy enough with that). I find it distressing when I think / feel that I'm phenotypically turning into a male... With respect to my gender identity... I largely reject gender role stereotypes... But I do 'tow the line' on some things (e.g., with respect to hair removal!). And my preference is certainly to do that... My gender identity is complicated, I guess.