Normal je, sayang, at 3 months babies do sleep a lot, boleh up to 16-17 hours a day depending on the baby. A few of my mum friends' babies were heavy sleepers at that age and they're fine now, so don't worry! Just make sure baby is feeding well, gaining weight, and alert when awake, kalau semua okay, let baby sleep. But if you're concerned pasal anything else like feeding or development, best check dengan pediatrician untuk peace of mind.