Metamorphmagus question

Suppose a child Metamorphmagus decides to turn into a member of the opposite sex. However, being a sheltered child, our Metamorphmagus has an incorrect idea of what the genitals of the opposite sex look like. Would they end up having genitals that do not resemble anything that exists in humanity? If so, would they still be able to urinate and defecate? If so, does that mean that they can simply change how their internal organs work? If so, does that mean they can heal their own injuries? The possibilities are endless!