All right darlin'...you're an
alumna...because you're a woman. And a bunch of us are
alumnae.
Men - one is an
alumnus and more than one are
alumni.
And your college's organized group of former students is referred to as
alumni, because it has both male and female members.
Informally, I'm an alum and a bunch of us are alums.
Sorry, that's just a pet peeve of mine!
Welcome!