Welcome to Susan's Place. I will start with the nickel tour so we are speaking the same language.
Gender identity is who you go to bed as.
Sexual preference is who you go to bed with.
If your comfortable with your gender identity, but you prefer partners of the same gender, then you would be gay.
If your uncomfortable with your gender identity then your transgender.
If your uncomfortable with your gender identity and you wish to alter it to the opposite gender, then your transsexual.
High prolactin can be caused by a number of conditions and your doctor will run tests on you to determine the cause. One possibility is a tumor and it would have nothing to do with your gender identity or sexual preference. It would just be a medical condition that may need treatment depending on the type of tumor.
I am a bit confused about your birth gender however testosterone is pretty unpredictable. I had natural exposure to it and I didn't grow much of a beard and no muscle. Others around me looked like adult males in the 8th grade. It depends on your genetics as to how you will turn out.
Because I am confused about your birth gender, I am going to provide two addition links that might prove useful. The first is
our WIKI where you will get a better idea what transgender is. The second link is the
"the transition channel" that would explore your feelings and would help you determine if your transsexual.