Yamato is female, period. See, there is a difference b/w identifying yourself as a specific gender because you feel in a certain way and changing your gender because you wanna pretend like someone else. Yamato simply has an unhealthy level of obsession with Oden, which made her delusional, and it won't be long before she starts realizing she's not Oden. Yamato isn't the same as, say, someone like Kiku.
Can you define a man and a woman scientifically?