Eh, normal range is around 11-16kg depending on your starting weight lah, but honestly every mum is different, some of my friends gained 8kg, some 20kg, and babies all came out healthy je! The important thing is you're eating well for baby, not stressing too much about the numbers, and your doctor says okay lang. Kalo you're worried, best to ask your gynae what's normal for YOUR body specifically, since everyone's journey is so different.