Randym Ys fail to make male names femynyn in 99% of cases (the exception, for me, is
Sydney only--and even
Sydney was originally male).
Stick with
Austin if you insist on using the name for a girl. But to me
Austin's 100% male. I would prefer
Augusta (my favourite), Austina, or even Austine or Awstinwen (see
Awstin;
-wen is sometimes used to feminise Welsh male names, as in
Bran and
Branwen) for a girl.
Miranda
Proud adopter of 15 punctuation marks; see my profile for their names.