Mirriel,
I hear ya' ! I have been living successfully as a male for so long that I wonder sometimes whether I am really transgender or just another boy that likes to wear dresses. But that constant itch in the back of my mind tells me that I need to keep my faith and continue my journey. I think you should do the same - dont give up!
To add to the excellent and experience-driven advise from the other posters, is something I learned from an excellent book I read. When you try living as a woman, really "live" as a woman. That means not only doing the fun stuff but also the things that can be hard to adjust to - taking routine care of your skin and hair, being constantly mindful of the details of your appearance, finding just the right clothes and make-up for the situation and being generally more neat and organized. If you are not put off by the "hard stuff" that is a positive sign that you may be transgender. Oh, one more thing - always sit when you are on the potty. It can be a hassle to peel off bodysuits, lingerie, hosiery, pull up dresses and skirts, pull down those cute leggings etc etc, then put it all back in order again. I practice this but have to admit, I still cheat once in awhile.
Sounds silly but the point is, how you deal with all the small little things that women do naturally, will be a good data point to help you sort out your feelings.
Good luck,
Miril