Hey mama, totally get the worry kasi ganyan talaga kami, pero good news na sinabi ng doctor mo na okay pa, yun na ang most important! A few of us mums had the same thing at 18-20 weeks and turned out our babies were just on the smaller side or dating was slightly off lang, so don't stress yourself too much. If your doc's not concerned na wala pang big gap, definitely trust that, pero if it still bothers you, you can always ask for a repeat ultrasound in a few weeks para makita kung consistent lang or nag-catch up na baby mo. The worry won't stop pero at least you'll have peace of mind!