Here's my advice.
WARNING!!!: Don't do ANYTHING I suggest unless you realise it is at your own risk! I have never been in a relationship, and I have no experience in this field. Side effects may include getting yelled at, locked doors, and a strange sense of alienation from your favorite TV shows.
Firstly, I would suggest appealing to her sense of reason. This is a general rule that applies to everyone. Give a valid point of view, and see how she reacts to it. Note: you did NOT appeal to her sense of reason before, you merely posed the question; actual bring up some factual, scientific points and opinions that cause serious brain-crunching. Let her see how there is factual proof that this could be healthy for you, her, your relationship, and all kinds of "anything else" you can think of.
If reason fails, appeal to her sense of humanity. Bring up the points that, as a human, you are more than just a person-you are a mind and a soul. Bring around the points that this is something that has troubled your mind, and that you are sure that this is something that can solve your psychological and personal unrest, as well as bringing around your discovery of yourself as a person.
Next, if your attempt to sway her with your humanity fails, appeal to her sense of emotional understanding. Being a woman, she is more accustomed to letting her emotions run freely. (This is one of the fundimental reasons why men fight over the most trival things or break stuff, and a woman's tongue cuts so deeply...not to say women don't fight.) Get emotional! (because IF you really plan on going on hormones, you better get used to confronting your emotions!) Show her that this means MUCH to you, and that it hurts your heart to have to hide your feelings, or be someone you arent.
Also, everyone here has already put it so adequately. "Don't expect her to accept this overnight." There are very few people who could accept a change like this-even fewer who could do it over-night.
Now, I am NOT saying you should manipulate her with these steps. Be genuine.
I have MORE to say but I am hungry, and my fish is getting cold. Besides, I don't wanna seem like a thread demon, typing until there is no space left.