Ay, ganyan talaga ang ultrasounds mama, lalo na as you get further along, mas lumalaki ang margin of error kaya hindi lahat mag-align perfectly! Honestly, sa third trimester, the difference between what your OB's dating scan shows versus your BPS is pretty normal na, especially kung ng few days lang ang difference, I'd follow your OB's calculation kasi yun ang consistent with your earlier scans (TVS and CAS both showing Sept 10), and your doctor knows your full history better. But definitely ask your OB directly about the BPS result at bakit may difference, kasi baka may valid reason or baka hindi lang siya worried; some doctors actually go with their own dating scan pa lang especially kung consistent na from the start. The important thing is you're monitoring closely and your baby's growth ay normal, diba? Trust your OB on this one mama, yan ang safest approach!