I don't think there were any bad intentions on OP's end, but the highlighted claim that a person is female and therefore has this or that genitalia is indeed transphobic.

Someone's probably going to show up and say "but it says 'female', not 'woman'!" Well, "female" as an adjective referring to people already means woman. A female doctor is a doctor who is a woman. And "female" as a noun (e.g., "the females") is a terrible way to refer to people, to begin with.

Nah, it's just a joke. Maybe a cisnormative joke, but as a trans woman myself I didn't think twice about it.

In my book, for something to be transphobic it has to intentionally discredit or attack trans people.