I feel the same way too and have just gone through a couple days of "what am I doing?!"...
I think there are things that we do to ourselves and ways of thinking that probably aren't particularly healthy and don't help. These are just musings so take with a pinch of salt!
No human is 100% anything relative to other humans...there is always going to be someone else who is more feminine or masculine, so we really need to truly embrace existing on a continuum.
So instead of focussing on gender, focus on your traits, because female is just shorthand for "I have more girl traits than boy traits"...but at no point are you really required to put yourself in a box in your own mind and certainly if it isn't helpful to you.
So forget girl and forget boy. You are just a human with mainly feminine traits and the real problem is that society tries to boil this down to binary thinking to make a complex thing a simple one, which while understandable, is doing a great disservice to that thing that is the human experience!
Ok, enough with the preaching here's how I "find myself" when I have doubts: I ask myself a simple and relevant question: "if I have to the live the rest of my life alone, would I rather be a boy or a girl?". For me the answer is an easy one that makes me realise that in isolation I know exactly what I want to present as. Things only start to get confusing when I think about other people and how I fit relative to them...(Will I be unable to find a loving partner if I do this, etc...)
So yeah, focus on making yourself happy by exploring your feminine traits without actively labelling it. Once you've made peace with yourself about how you feel, your internal model of the situation will be much more resilient to the thoughtless opinions of others.
x
P.S. Here's a news article that may interest you:
https://www.theguardian.com/science/2015/nov/30/brain-sex-men-from-mars-women-venus-not-so-says-new-study