Haha congrats on week 13, so exciting! Honestly the mouth open thing doesn't really tell us anything la, but a few of my mum friends swear by the nub theory at your scan stage, if the nub is more angled up, usually boy, flat or down is girl, tapi honestly it's 50/50 palsu or betul The NIPT results will give you the real answer soon, so yang penting tu sehat je baby! Can't wait to hear what you're having!