The OP's sister is physically a WOMAN...with breasts, vagina...BUT NO UTERUS.

What the OP failed to state is if its a complete or incomplete type.

Complete androgen insensitivity prevents the development of the penis and other male body parts. The child born appears to be a girl. The complete form of the syndrome occurs in as many as 1 in 20,000 live births.

Incomplete AIS can include other disorders which is associated with breast development, failure of one or both testes to descend into the scrotum after birth

what's wrong with her is internal (with her endocrine, reproductive and/or immune system)

She was raised as a girl...looks like a girl...She don't have a PENIS or scrotum/testicles....so she's not a "hermaphrodite".

She can never marry...or have kids...that's the sad part.