Ahhh I feel you, confusing betul kan kalau counting methods berbeza! Actually normal jer lah, apps sometimes calculate from last menstrual period (LMP) while doctors go by ultrasound dating, so ada 1 week difference is very common. A few of my mum friends had the same confusion, so just go with what your nurse confirm since they based on your actual scans, that's more accurate than apps! Anyway you're so close to third trimester, congrats mama!