Ahhh mama, i understand why you're worried lah, but macrocephaly or size difference yang minor ni memang quite common, don't panic dulu okay! A few of my mum friends had the same concern during scan, and their babies turned out perfectly fine bila lahir; sometimes the measurements tu just estimate saja and baby's kepala might catch up atau grow proportionally je. The good news is doc sudah refer you to specialist, which is the right move, they'll do proper assessment and confirm everything is okay or advise next steps dengan lebih detail. Doakan jer semuanya smooth ye, and do follow up dengan pakar supaya boleh stop the worry faster!