Baby eating too much??🤷🏽‍♀️

So I had my baby girl early on 12th jan at 36 weeks so she’s now 3 weeks + 4days old.. she wasn’t due until the 9th Feb... her birth weight was 6lb 10oz.. she went down to 5lb 13oz by day 5 due to incorrect breast feeding so I put her onto bottles and she is now up to 8lb 4oz (5days ago she was 7lb8oz)

She drinks Aptamil formula milk and has roughly 4oz (120ml) every 3 hours.. but towards the end of the day she was wanting every 2 hours so I have just put her up onto the Aptamil number 2 (follow on) milk for the last feed before bed.. the health visitor said this is ok...

What I want to know is how much is your baby drinking? And how often? I feel like 4oz is alot for a 3week old preemie that technically shouldn’t even be here yet.