Eh jangan risau dulu, usually babies catch up one by one, some head dulu, some kepala last! Tapi since nurse dah mention the red line, better you follow up closely at next appointment and document everything (measurements, milestones dia buat) so you dapat cerita yang clear kat doctor nanti. Few of my mum friends had similar worries and turned out okay after doctor checked, so just go with the process la and see what specialist says, sometimes it's genetic, sometimes just slow growth pattern. In the meantime, make sure feeding dia okay, she's hitting her milestones (bahasa, motor skills, interaction), and she's happy and alert, those matter more than head size alone. Hang in there mama, one step at a time!