Yay, congrats sa baby mo! Ang gain ni baby mo from 2400g to 4200g in 6 weeks ay 1800g, which is really good, typically babies gain around 150-200g per week in the first months, so you're on track talaga. A few of us mums noticed our babies had similar gains and the pediatrician was happy, pero para totally peace of mind and to make sure baby's feeding well, just do a quick check-up with your doctor or pediatrician to get their seal of approval, they can also monitor baby's length and head growth overall. You're doing great!