Ay, don't worry too much! A few of my mum friends had the same experience sa 30 weeks, at honestly ang ultrasound measurements ay hindi pa super accurate sa timing na yan, kaya pwede silang off by a couple of pounds pa. Ang importante talaga ay kung wala nang ibang signs na may problema sa baby based sa ultrasound itself, like abnormalities or other concerns, kaya that's usually a good sign. One of my friends had a baby na parang measuring small din pero healthy pa rin, so it really varies from baby to baby, some babies lang talaga ay naturally smaller at magugrow pa nang normal lang. Since this is your little one though, definitely worth asking your doctor or OB kung kailangan mo ng follow-up scan or referral sa specialist para sa peace of mind mo, just to monitor lang kung paano babago from now til delivery. You'll feel better once you've talked it through with your doctor directly!