Ashley, that isn't really a whole separate person haunting you. It's just a part of your own mind raising that self-doubt, the primitive worrier still wedded to an obsolete self image. Like Jentay says, you just have to push on through. That helps the long, slow process of updating your internal self-image to the point where that doubt fades away.
I've been out for a year, on HRT almost 9 months, and full time for 4+ months, and you know what? That stupid Doubt Monster is still here. That 'he' is really just a part of ME, and is slowly re-integrating, dissolving away until only I will remain.
The process takes a long time. Really long. Trillions of neurons, hundred of trillions of little neural switches all holding onto state accumulated over a half century of life don't just reset overnight. When I got dressed this morning, I turned and looked in the mirror, and I saw MYSELF. No 'dude in a dress', just ME, and I was overjoyed. I damn near started crying. That is how rarely I get to fully be just me, that when I am and there are no doubts, I am so surprised at myself and joyous at being me. After all this time, this is still not an everyday event.
When I don't quite feel just ME, when the Doubt Chihuahua (that's all the monster is these days) is yipping at me, I still get my looks right, paste on my best smile, and head into the world. Faking it til I make it. I feel better pretty quickly these days, and can get past that nuisance in minutes instead of hours, but it is still there. It IS better, and I am constantly improving.
Just push on through, Ashley. You know who you really are. Be true to yourself, not that silly slow learner in the hindbrain.