Aiya normal la sayang, setiap baby develop at their own pace, a few of my mum friends pun ada babies yang diam je sampai past 2 years, then tiba-tiba membanjiri dengan ayat panjang hehe. By 1 tahun 7 bulan, some babies dah banyak cakap, some baru few words je, so don't worry too much yet. Tapi kalau you're concerned, boleh check with your pediatrician next visit just untuk peace of mind, because they know baby's development history better kan. Meantime, just keep talking to him, baca buku, dengarkan lagu, dia absorbing more than you think even if dia tak cakap banyak yet!