Very confused and overwhelmed first time mum.

How many oz in 24hrs should a 3month old who weighs 13lb have? How would you split that over the 24hrs? 

Our health visitor said go off baby's ques but I'm concerned we could be over feeding as baby can spit up sometimes after feeds, be gassy and sometimes foul smelling nappies. From looking online this can be a sign of overfeeding. 

We've looked on the NHS website and it says 150ml to 200ml per kilo of weight in 24hrs so that would be between 31oz - 41oz. 

I'm just so confused and overwhelmed. This is our first baby and I want to make sure he's getting enough but not too much.