Being biologically female means having a body that is observably organised to produce large gametes (eggs), as opposed to a body organised to produce small gametes (sperm). A woman is female whether her eggs have been fertilised or not. A man can never be female.
@nyaraVT This is really very simple. A female body is *organised* to produce large gametes. It is irrelevant whether the female in question is too young or too old to produce viable eggs. It is irrelevant whether the female's eggs have ever been fertilised or resulted in a birth.