Female or not?

So I got my self a lovely young whiteface male a few months back and was in the market for a female for him. Came across a beautiful bird that was listed as female. So I bought her and brought her home.

Now I've had these birds for a couple of months now so they'd be around 10 or 11 months old. I'm starting to think that she may be a he. These two are aviary birds but I have 2 females indoors as tame birds. Both are quite a bit stockier than the female outside. She has the same build as the male.

I'm probably wrong but the other thing that makes me question is total lack of interest in the nest box. Even though it's off season here my bourkes, turks and budgie hens are still in and out of their boxes. Not my cockatiel.

Here are some pics. Still too young to tell for certain but I'd like to hear others opinions.(Apologies for the quality)

Since you've had he/she now for awhile, is the bird attempting to whistle or chatter at all?

markings indicate female. She's a pearl which is sex linked. She's likely molted at least once by now and the pearl marking is still strong and present. Shes still young, my cockatiel is about a year and a half and has only just started exhibiting strong hormonal behavior.

I've had a whiteface male that never whistled, chatted or any of the normal vocal behaviour that you expect for a male and I currently have a female that whistles and attempts to talk. In saying that she has never attempted to do anything more than either hiss at me or squawk.

As she is under a year old I wouldn't have expected a major moult yet so I wasn't taking the pearl into consideration. I was looking at build and behaviour which is massively inaccurate in sexing a bird. I think you are probably right in saying female.

After the young female I recently gained that talks and whistles I question everything I thought I knew. It will probably turn out she is a he and I was wrong with my gender ID. If I can get pics I might start a new thread for her.