Nub when baby won't move its legs!!

Danielle • Mommy to a precious little boy born 12/17/15 and full time working mom! I love my little family!
I have been trying to guess baby's sex. I had my nuchal scan last week at 12+1 weeks and baby kept flipping over on its stomach. The tech finally got baby flipped on its back but I can't see a nub because the leg is in the way. Does this mean anything specific to the nub theory?
My husband swears it's a boy and we find out for sure July 3rd but I'm dying to make guesses.