nub theory or skull theory?

If the circled area is the nub I'm guessing boy but people I've shown pic to don't think it is the nub.
Anybody have any theories?

Forgot to add it was taken at 13 weeks and 2 days ��

Not seeing a nub, sorry. Do you have any more?

I think what you circled may be part of the leg. And I think I see a nub near the bottom of the circle pointing straight if not down. Guessing girl.

Bunnywabbit, 2 more images, baby was being awkward and stayed on belly the entire scan x

Not seeing anything on these either, sorry x

Anybody any other guesses based on skull theory?