The Buff is a roo. I've had more than plenty of Buff Orpingtons and all of my full grown laying hens have had a medium sized comb and waddles once full grown, but it takes a long time to come in. They typically don't start laying until 20-24 weeks, but already your Buff has the comb and waddles of a roo. They don't necessarily have spurs yet, and some females even do get spurs, so that's never a guarantee. I have a Buff roo right now that is 13 weeks old, not crowing yet, but is a boy. I will upload some photos for you to see the comparisons between a boy and girl.

My Buff Cockerel at 13 weeks. Not crowing yet.

My Buff Orpington Pullets at 13 weeks.

Not Mine, but a Buff Pullet around the same age as yours.

And here's one of my full grown Buff Orpingtons with her comb and waddles, and her
egg of course, lol. This picture was used for some customers so it has the baby pics on there as well, but
obviously that part isn't relevant to your situation. Lol. Sorry.
So you can see through the photos that it takes quite a while for the comb and waddles to come in for a purebred Buff Orpington. That's why I believe yours to be a boy. Hope this helps.
My Buff Cockerel at 13 weeks. Not crowing yet.
My Buff Orpington Pullets at 13 weeks.
Not Mine, but a Buff Pullet around the same age as yours.
And here's one of my full grown Buff Orpingtons with her comb and waddles, and her
egg of course, lol. This picture was used for some customers so it has the baby pics on there as well, but
obviously that part isn't relevant to your situation. Lol. Sorry.
So you can see through the photos that it takes quite a while for the comb and waddles to come in for a purebred Buff Orpington. That's why I believe yours to be a boy. Hope this helps.