2 week 3 day old eats a lot

When my son was born he had a issue with feeding so needed a neonatal stay and a feeding tube (only spent half hour with him after birth before he was taken there) then he struggled too suck on the bottles the neonatal team gave him (because of this he wouldn't breast feed but I do express and he has formula)

Well now he eats around 130ml then can have a nap and wake up an hour later and eat another 40/60ml and then still want another 120/140ml three hours later, he definitely doesn't have a issue feeding now!