a low standard of that certain breed that isn't bred for showing and most likely just for egg production, If you were to ever show her as a Leghorn she wouldn't have much of a chance to win anything. Although i'm almost positive your girl isn't a White leghorn but an Austra white.
Either a poor quality white leghorn or an austra white. (Which is an Australorp mixed with a White Leghorn) But yes, She doesn't look any older than 3 years,