Ay nub theory, haha! Honestly, I'm not really a believer sa ganyan, sobrang hit or miss talaga based sa ultrasound angle at tech quality, kaya mas nakaasa ako sa actual anatomy scan ng OB namin. One of my mum friends tried to predict based on nub theory with her first two and both were wrong, so ngayon we just wait for the 20-week scan na talaga na makikita ng doctor. What week ka na anyway? If you're curious, better to ask your OB what they see during your next check-up!