How much is enough?

Hello! I am totally a new mum with 8d.o. boy and we have got a problem with his feeding.Because of a certain issue I am not breastfeeding him and he is on Nan Pro Milk (not powder). In the beginning he was eating like 8-10 times every 3-4 hours and it was aroung 600ml per day. For last two days he wakes up every 1-2 hours and eats the same amount, just more often and yesterday his feeding came up to 800ml. So what would you advice - give more per feeding or let him wake up every 1-2 hours for now?

Cheers a lot for your help in advance.