Hey! Every baby size and progress is different! Please do not compare your baby with other baby! Feed on demand.. if she cries 2 hours after milk, check whether she is experiencing any discomfort, needs a diaper change or is feeling too hot or cold? If everything else is ok, then yes please proceed to give more milk..
Hi mummy you should follow baby cue. Just give more and not starve your baby. You can give more and drag timing too. 3.1kg to me me is quite light. My baby birth at 36 weeks weighing 3.2kg and 1 month later weighting 5kg.