I've consult my doctor's opinions la. No need to worry so much if your bb is healthy and active. Cos their growth will be slowed down after they're 6 months old. I think you will remember when you bb was new born to the first few months. Her weight and height was increasing sharply. Besides, she would increase her weight 1-2 pounds each month.
However, once the babies are about 6 months old. The growing rate will be slowed down. No need worry wor.