there are only 2 genders
It would not. Hermaphroditism doesn't exist in humans. There are intersex humans, but not hermaphrodites. Hermaphrodites have both male and female reproductive functions. As far as I'm aware, there have been no confirmed cases of this in humans specifically. Lots of fish and plants are hermaphroditic though!
I was born with an working testicle and an working overy.
Approx 20% of humans are born the same way, the humam body plan does not allow such persons to be reproductive in both male and female capacities however closely related animals do, and humans can be born looking like they are female, then turn into males during puberty. It is likely the oppisite is possible as well, however retracted testicles are painful and cause complicstions so Dr's halt the process.
So what sex am I? What sex are these people whom are born girls and naturally turn into boys during puberty?
Gender, is how sex interacts with socity, in a strict scientific rational raw state of nature biological reality; there are no genders.
None, notta one. If you where born on an empty desert island you would never grow up to be any gender at all.
They are again our biological reaction to social pressures. Not biological.
FYI, 20% of males do not have a Y chromosone. It used to be assumed that 17% of males lost thier Y chromosone, but now we know that 100% of Y chromosones are.. Blank. Empty. Nodda thing on them. Its all carried in the X. The mappining was finsihed and confirmed this year (2024).
So... Not so binary is it?