I've definitely had plenty of dreams where I have been female. Those are always my favorite and usually I wake up quite happy. Until reality sets in, but remembering them helps than if I didn't have those dreams.
And to get a little metaphysical with your question, that's true for everyone that is trans*. Their subconscious mind says one thing but their conscious mind (the one influenced by society and environment) tries to say another. You have always known you're female (if you are, a question only you can answer) in your subconscious. Sometimes, it just takes longer for the rest of you to catch up. Especially as you've been raised as a male. Society says you are a male. Trusted doctors say you are male. Family says you are male. Ergo, you must be male. At least, that's how the conscious mind sees it. Sadly, the conscious mind is an idiot. Easily fooled.
The subconscious mind, on the other hand, is almost impossible to deceive. It takes in and processes so much information that you are never aware of. The very fact that you are considering the possibility that you aren't entirely male is a clue in and of itself. Many cisgendered people would never consider the possibility beyond "Wonder what it'd be like to be female". Their subconscious mind is male, their body is male.
The question is, how far along the spectrum do you lean? Say, for example, are you 30% male, 70% female? 50/50? Questions only you can answer with a lot of time, effort and patience. You'll probably never have exact numbers but you'll eventually discover to which side you lean more. Then you can decide where you want to go with it.
But, the most important part is to take things slow and be open. Be patient with yourself. After I started actively thinking about whether or not I was really trans, I spent almost a year in self-exploration before deciding that yes, I truly do see myself as female. A good portion of that time, however, was spent between saying "yes" and "no" to the girl inside of me. I couldn't make up my mind because sometimes, I did feel like I was male. While I still have those feelings, which I guess would make me more gender fluid than typical transgender female, I lean heavily toward female the vast majority of time to the point where transitioning isn't really a choice for me, but a need.
XD No idea if any of that was what you were looking for. I just got done writing a few chapters in my novel so I'm a bit overly wordy still.
