Mine were quite tough to sex for a long while, all looked female at first then all male...then 1.2 in the end. But size told me more than the bulges did honestly, the two females shot past the male in growth around 6 months....once they were both 5 g larger it was pretty clear. Then looking at the underside of the tail it was hard not to say "oh, obviously, that's it"

Hard way to do it I guess if you have a singleton....