Take your pick of people with relevant credentials, such as PhD Developmental Biology or PhD Developmental Genetics, that signed a statement that is exactly what I'm saying:

https://projectnettie.wordpress.com/

[..] Biological sex does not meet the defining criteria for a spectrum.

Or someone else:

https://www.nas.org/academic-questions/33/2/in-humans-sex-is-binary-and-immutable

the objective truth is that sex in humans is strictly binary and immutable, for fundamental reasons that are common knowledge to all biologists taking the findings of their discipline seriously.

Even in your best case, when you look at one of the few extremists pushing for a nonsensical redefinition of sex, they still directly admit that gamete size is binary, directly contradicting the strange claim above about a third gamete size:

https://sciencebasedmedicine.org/the-science-of-biological-sex/

When it comes to gametes, these are strictly binary – egg or sperm

I mean c'mon, this is just silly. Crack open your textbook and read it.