sometimes I tell doctors I was born without a uterus and that solves / explains away the issue without disclosing trans status

some women are born without a uterus or have their uterus removed - so it’s possible to be a woman without a cervix 🤷‍♀️

EDIT: that said, I don’t think you owe him an explanation and his comment could be seen as inappropriate, and regardless my point is there is no need to jump to transness as an explanation even if you felt you needed to explain something (e.g. to a doctor).