> I am a woman when writing this sentence but a man after I'm done.

This actually proves my point even better than I already had. If you can just make it up and say you are whatever gender whenever you want, then the idea of transitioning between them isn't actually a real thing, it's just all in your head and more importantly - the idea that anybody else should respect it is absurd.

Also, you have declared that you can't define what constitutes different genders, nor have any idea of how many genders there are. So, it's all make believe.