Most standards of care have transgenderism labeled as a psychiatric disorder, which is a huge debate in and of itself. The issue there is labeling it as disease which some feel is humiliating and debilitating. It also makes the transitioning process even more frustrating, as you have to have a psychiatrist confirming the diagnosis before beginning hormones or being approved for surgery. Plus, you have to find a psychiatrist that will work with transgender patients. Many don't.
It's a very complex issue and I understand that it's hard to wrap the mind around and the best I can say is that, yes I really do feel that my sex and gender do not match.