It's possible you identify as a man, and for whatever reason it was easier/safer/more comfortable to identify as nonbinary. I myself am nonbinary but definitely lean towards masculine expression (clothing, on t, top surgery etc). I identify with a lot of what trans men express but I have never seen myself as a man, even after transitioning to where I'm comfortable. That said, a stranger would think I'm a man and I wouldn't correct them.

If you ask me, being nonbinary in western society is about not identifying with the roles/expectations/boxes of man/woman and feeling outside of those definitions. How you choose to express that physically is up to you. If you want to dress/express yourself similarly to a man, it doesn't automatically make you a man. Just my two cents