12w2d Nub Theory Guesses: Would love to hear what you think!!

I'm due in May 2018 with my second baby. Would love to know what your guesses are based on this ultrasound from when I was 12w2d -- I'm thinking Nub Theory is probably a safe bet using this picture?! Cant' wait to hear your thoughts, and thank you in advance! Attachment 38194

Its hard to tell as its a bit blurry but i think possibly boy as im pretty sure i see a shadow above the nub