I used to not care too much about gender, but I was really bothered by stereotypes assigned to me, but even then I accepted that I was just a cis guy, more recently my friend came out as agender, so I asked them how did they found this out.
After listening to the "story" I realized that I identified too much with it, so I started to think more deeply about it, after a while I realized that I still had a small part of me that felt like a boy, maybe 5%, so the question yeah, can i be a demiboy even if only that tiny part of me is a boy? Or agender is still the best definition for me?