12 week 5 day ultrasound-no nub to be seen, how about skull theory?

I had an ultrasound at 12 weeks 5 days. During the ultrasound the technician said that she thought it was a boy because of the "doo-dad". I didn't know about the nub theory at that point, but when I got home I started doing some research and I am not sure about her boy prediction. Could anyone take a look at the ultrasound below, I know there is no visible nub, I am not sure what that is on the bottom left, but could you guess based on skull theory? Thanks for any help with this, I am kind of obsessed!Attachment 4190