Ahhh susah nak cakap betul-betul at 26 weeks la, terutama kalau baby position tak cooperate! A few of my mum friends kata even the sonographer sendiri sometimes say "looks like a boy but not 100% sure" The nub theory boleh try tapi jangan expect 100% accurate, your next scan will be clearer, especially if baby decides to show their business properly this time!