You can't be serious.
Clearly she DOES have some sort of idea of how babies are made or she wouldn't have asked that blindingly obvious question.
That conversation with the angel was only about her conception of Jesus. It in no way referenced her future plans.
Young's Literal translation says this.....34And Mary said unto the messenger, `How shall this be, seeing a husband I do not know?'
She is clearly revealing her knowledge of how babies come about by commenting that she's a virgin and wondering how she could become pregnant since she has not yet had sex.
But that comment makes no sense if she had planned to have children with Joseph. Obviously she did not plan for that.