So I decided to look into the whole "gender is a social construct" debate. But before I dive into this Internet shitstorm, I just want you to keep one crucial thing in mind: sex and gender are two different things. Biological sex is based off of your sexual reproductive organs and there are only three: male, female, and asexual. Gender is social and cultural differences between male and female. Keep this in mind.
So I did a quick search of "societies where there is more than two genders." And what I found is that there are quite a few societies that have more than genders then just female and male. Some of these stem from Native American peoples and their concept of the Two-Spirit. These include the Mojave and the Alyha, which was a boy who expressed feminine traits, ritualistically becoming a woman during their coming of age ceremony. Another example is the Machi shamans of the Mapuche people; the Machi are said to change genders frequently in rituals the shamans conduct on themselves.
Going over to Asia, among the Hindus of India, exists the Hijras. In the culture’s definition, a hijra is one born as a male, but adopts the clothing, behavior, and occupations of women. Their status in society is neither male nor female, neither man nor woman. The inverse of this is the Sadhin although they are much less prominent (and there are several other key differences as well, namely that the Sadhin must be celebate).
I could go on forever. These are actual genders in different societies worldwide.
Which leads me to the situation of the "male/female only" gender system here in America. Despite pointing out that there are societies with more than two gender, I have no opinion on billion and one genders that "seem to have been made up." Rather I treat all people with respect and kindness. I don't go shitting on people because of how they chose to define themselves, especially if it's not to the person's face. Only edgelords and keyboard warriors do that.
Ultimately, however you choose to define yourself is up to you.