I went to a presentation on Transgenderism at RIT last weekend because it's something I'm very curious about and lack information on. The speaker was a female-to-male transgendered individual that (from what I've heard) had been taking hormones (testosterone) for about six months. I say this, not really because it's relevant to the entry, but to show that the information was coming from an eminently qualified individual.
And yet when it came time to discuss and define transgenderism, and more broadly, gender and sex as a whole, he stumbled. And thought. And hesitated. And really what we discover is that even someone who has (literally) a lifetime of experience with these issues can't find any sort of appropriateness within the various labels. It seems that labels don't really work so well. We like to put things in categories, but people are too unique for that to be done with any sort of effectiveness.
My girlfriend has said on numerous occasions, "I don't understand why I have to be straight or a bisexual, or genderqueer, or whatever. Why can't I just be a person?"