Do not transition. Self-respect is a human right. Transition is too great a price to pay for self-respect.
Transition is a way to get self-respect, and so is tempting. You have never felt you are a real man. You feel less. You try to make a man of yourself, and always feel inadequate. You have the shameful secret that you cross-dress.
But what if you are trans? Then, Being a Man would be obviously wrong for you. You could express yourself in a way which fits your personality. You would be free. You would have The Answer- you know why you have never fitted in, and what you can do about it. The delight you feel when contemplating transition and the misery you feel at presenting male is confirmation. Having a long and difficult journey to reach freedom, every step you take on it delights you. You are in the pink fog, a wonderful term I got from my friend Joanna Santos, whose whole post is worth reading: Dreaming about the aspects you think you would relish about being a woman can lead you into a deep pink fog which can sometimes confuse things.
You ask yourself if other theories fit. Autogynephilia, perhaps: “Men trapped in men’s bodies”. No. I don’t think Renee Richards entirely cuts it either- “a lifelong committed transvestite”. Some object to the term transvestite, coined by psychologists and formerly used as a diagnosis of a disorder. “Cross-dresser” was coined by the community. Cross-dressing is a harmless way of reducing stress. If it arouses you sexually, that is nothing to be ashamed of: the clothes are lovely, and humans get horny at all sorts of things. Yet that is not all you are. You are not a failed man with a disgusting habit, and the habit does not define you. It is a harmless habit, though. It need not be all your life.
My other theory is that you are a “beta male“. You don’t fit “alpha” models of masculinity, but beta is the upgrade! You have ways of being which are a blessing to a community. You are soft, gentle, peaceful. You are empathetic and conciliatory, and like to fit in- this is a blessing, but has been distorted, to cause you to try to be a Real Man.
If you have been shamed by not being a Real Man, transition is a way to self-acceptance and self-understanding; however if you have been shamed, that is a psychic wound which can distort how you see the world and yourself. You went along with it for a time. You tried to make a man of yourself. You could not, and your shame increased, but you could not because it was not right for you. Find a therapist who can help you appreciate your own beauty. If you find someone who will love you for yourself, rather than for a false image of you, that will help.
I believe there are trans women who will be fulfilled by transition. I would never want to cut off the path to transition. But it is not the best way for everyone who starts it, and you may face discrimination and hostility.
Rather than a real life test, where you must change your name and agree never to present male again, I would recommend a period of exploration, to include extensive psychotherapy. You could present female or male, and you could try to express your feminine side while presenting male. What do you want?
Who are you, really?