I essentially folded the moment my assertion in my "cis-ness" was challenged (got asked what pronouns I preferred for the first time, had a thought that "maybe they/them would be fun" come into my head, and went from there.) Over the years since having that first realization, my perception of my own gender has shifted and changed as I've tried different labels and pronouns, accepted some, and rejected others. Right now I'm in a pretty comfortable position with my gender (firmly trans, wanting androgenic HRT, not identifying with being transmasc/a trans man) but who knows, things are subject to change in the future as I gain new experiences and discover more about myself.

I think what helped me was gaining the realization that wanting to be whatever gender you want to be is all the proof you need. I used to be stuck in the idea that there is some "essence" of transness that I was missing, therefore I wasn't trans. But there isn't. You don't need to experience dysphoria to be trans (though it's pretty common for trans people to realize that they were, in fact, experiencing dysphoria and just didn't know that's what it was.) Cis people don't find themselves wanting to be other genders. I know, it's weird.

Good luck on your gender journey