Okay, so please take everything I say with a grain of salt, because, while my experience as a transgender woman is adjacent to this topic, I do not have the personal experience of someone who identifies with a nonbinary gender.
As The Aspiring Archivist noted, gender identity, expression, and roles are all distinct facets of a person, and I think a good way to understand that on a deeper level is to look for where it appears in your own life. Like, if I were to ask you how you see yourself on a fundamental level, I am willing to guess that, among many other things, the word "man" might come up. If this is the case, my question to you is: Do you see yourself as a man because you do what you feel are masculine things and express yourself in a way that feels masculine to you? Or do you see yourself as a man simply because you feel, deep inside yourself, that you are a man? This is purely about how you feel, so there is no right or wrong answer! For myself, at least, and many other queer people I have met, the second one feels more true; we identify as the gender we feel ourselves to be. Even if I do things that I see as masculine, that does not make me feel like any less of a woman or any more of a man. Extending this, there are many people who, no matter how they view the way they express themselves, don't see themselves as "a man" or "a woman", simply because who they feel they are does not feel like either of identities. To use an analogy, as someone who wants to make a living as an author and so is probably very passionate about writing, have you ever gone for noticeable amount of time without really writing anything? If so, did it make you feel like you were any less of a writer for it? In another example, which I hope is not overstepping for you, I noticed in your bio that you are a member of the Church of Jesus Christ of the Latter Day Saints. Do you see yourself as a part of that faith because of the way you act? Or do you see yourself as a part of that faith because you feel, deep inside yourself, that you are a part of that faith? Ultimately, I just want to give you questions like these to think upon, because I believe that the best way to better understand someone else's experience is to look for pieces of that experience in your own life. Other people can help with that, but you are the only one who can truly find those connections, because, as evidenced by all the assumptions I have made in trying to help you reach that understanding, you are the only one who truly knows how it feels to be you. Does that help?
Finally, I just wanted you to know that I do not find your question at all offensive or disrespectful; in my own opinion, the courage to be vulnerable by asking a question like that, and the honest desire to grow one's own understanding and empathy through such a question, is deserving of more respect than I could put into words. Trying, because you believe in it, is so much more important than saying what you know is correct without believing in it. Thank you for trying.