Very confused about my budgie's gender o.o Help?

Okay, so first off, let me say that Mick Jagger is like by far the coolest budgie name. EVER. haha I would've never thought of that, but I do have four adult budgies and 6 baby ones so, I might just end up naming one of my birds Mick Jagger, but anyways...I'm pretty sure that Sherlock is a girl. Just by looking at his/her cere. But for now, I'd mark that as undefined gender. When budgies are young, you can't really tell if they're a girl/boy. But maybe wait a couple months and it might be a little more visible. If not, go to a vet.