The issue of “dysphoria”, unhappiness, your subjective experience of gender and how you feel about your body are a lot more important than a surface-level appraisal of whether or not your history or behaviours are consistent with the diagnosis of a certain “gender identity”. This isn’t because looking at dysphoria can work similarly to the pursuit of “gender identity” through narrative, instead indicating some “neurobiological predisposition” or “brain sex” that would have a deterministic relationship to gender or what you should do regarding transition (already got into this a bit with the hypothetical “brain scan”)… it’s more important because these questions pertain to the specifics of what you can choose to do that might make you feel happier and more comfortable with your body.
Gender comes later… more as a way of just saying whatever you want to say to other people and have them understand about that stuff, like your body and feelings about it and how you want to be treated and how you experience your sexuality through your body and all that. It’s mostly just about expressing whatever you feel is important express, and important for other people to understand about you.
Those questions about your feelings about your body aren’t any less subjective than anything else, though. And they’re bundled up in all kinds of distortions and shit that can be totally misleading and confusing and weird: what do you want to do because you want to experience your anatomy a certain way, what do you want because it would make you feel more yourself, what do you want because it might be more pleasurable or more in accordance with your sexuality, what do you want because you want to be pretty or beautiful or handsome, and what do you want because that’s what your cultural context has taught you someone of a given gender’s body is “supposed” to be? See: confusing as hell.
But at least they don’t imply a false objectivity. At least it’s about how you feel and about what you want, not about what you are.
Natalie Reed, How Do I Know If I’m Trans?