LOL Key Lime is adorable (and an adorable name) She looks like a girl to me
Just be careful about adding her to your other keets (in a month after quarentine right..?
) It looks like you currently have a male and female from your avatar and most of the time when there are more females then males the females will fight eachother for the male causing injury and sometimes even death. There are people whos 2 fems and a male get along great though so I'd just watch them for a few days after introduction, If Key or Mrs. White look like they're getting picked on, don't hesitate to remove key from the cage (After all weather she's the picker or the pickee, she's the one that changed the situation) and get her a buddy as well (male if you plan on putting them all together, female if you plan on keeping lulu and white separate
Oh wait... I jumped the gun... shes dominant pied. So really it depends, is the cere the light pastel blue it looks like? or is it more bluey purple. The first would indicate a girl whilst the second would indicate a boy. Watch for white rings around the nares (any white at all actually) that would also indicate that she was female
She's gorgeous though and she looks very healthy i would say she's 6 or so month old though because her bars are spotty at the very least meaning she would have to have already molted once or be molting right now..