Consider the following statements I could make about myself:
1) I am actually a woman who is masquerading as a man in order to make a living.
2) I am a man who loves to crossdress
3) I am bi-gendered or two-spirited person
4) Being transgender or transsexual or a crossdresser is a form of mental illness or sexual depravity and I am suffering from this.
How do I know which of these statements about myself is the correct one and how do I prove it to someone else? The answer, besides my obvious current biological reality is that I cannot know for certain.
What I can do is convince myself with my most resolute energy that one of them is correct and conduct myself in a manner that reflects that decision. Because we lack so much information in this field you are left to your own devices and it becomes incumbent upon you to find your own truth.
I have been able to make certain conclusions over my reflection process of course. The vast majority of us are not mentally ill and are highly functional so I can remove number 4 from the list but the other 3 scenarios are trickier because there we enter murkier waters.
But the mere fact that you are able to remove that last one should be a huge boost to your psyche.
In my own case when I finally stripped everything down to the bare bones, the answer became a deceptively simple one:
I am me.