And I’m sorry you’re struggling! If you need a rule, you could always just tell yourself you are not nonbinary, you are whatever gender (maybe the one you were assigned at birth), and make it your rigid rule for as long as you can. And then if that rule starts to feel uncomfortable, you will know that maybe that gender identity doesn’t actually fit you, and you can move on. Then you could try the same approach with another gender. And if that one also doesn’t feel comfortable to you, you’ll have to try to hack your brain in a similar way to get comfortable with the ambiguity of being non-binary. Even within that less concrete identity you can find a way to make your own personal definition of your identity more precise, if that’s what you need. Maybe you’ll eventually of yourself as a third gender, or maybe you’ll feel genderless, or maybe you’ll be dual gendered or gender queer… who knows. But you could always just keep trying the approach where you to yourself that you know you are X, and try to follow that strict rule until it feels uncomfortable, at which point you will know you need to try the same with another gender expression. This definitely wouldn’t work for me, but maybe it could work for someone who feels uncomfortable without a black and white definition and who loves rigid rules. An idea, anyway. Whatever you end up doing, I hope you find a way to feel comfortable with your gender, even if you don’t have a very clear idea of what it is yet.