Aww, nub theory! Honestly di ako expert dito pero I've seen a few of us moms try guessing based on that angle thing, hehe, sobrang hit-or-miss talaga ang accuracy nito kaya take it with a grain of salt lang! The safest way talaga is yung actual ultrasound with your OB, pero I get the excitement ng guessing game, lol. If you want to share the pic I can give you my mom-friend opinion, but remember it's really just for fun, the real answer ay makikita niyo na talaga sa proper ultrasound soon!