Why, may I ask, should a nickname that is simply a chopped-off shortening of the real name, be only legitimate for a male, not for a female?
Alex | andra and
Chris | tine are JUST as legitimate as
Alex | ander and
Chris | topher etc. Nowhere does it say that those shortenings have to be male. That's YOUR perception. And are you not aware that some 'girly' nicknames are masculine?
Christy is a common nickname for
Christopher in some places, not to mention
Mickey for
Michael,
Nicky for
Nicholas and
Vinnie for
Vincent.
Most nicknames are legitimately unisex, and most people realise that they have to be a little careful with unisex names until they've worked out the gender of the person involved. It's got nothing to do with sexuality or to do with hiding your gender. It's just the way our English-language naming system works.