I have had the same issues! I recently adopted Charlie, a beardie who turned two in June. The previous owner said a vet had told her that Charlie was a female, but there was some doubt. I watched videos and read articles and I'm pretty sure Charlie is a male, based on his hemipenis. Then yesterday I read about the femoral ducts and that article said that not all males have them, but absolutely no females have them. Charlie has them so I'm sticking with my assessment.
The sad thing is, the vet who couldn't tell the difference is the only exotics vet in the area (rural midwestern town.) I hope to never need her services.