Formula milk. Plz advice what is this!

Plz advice me which is best formula milk brand I am using nan 1 I have a baby boy ( born at 35 week) his birth weight was 2.23 now he is 3.550 I give him breast milk but he still gets hungry and I give formula as earlier he was not breastfeeding plz tell me how much formula milk I should give at a time how I can calculate the dose and how many times to feed after breastfeed plz advice as somedays he just vomits whatever he drink like even breastmilk n formula while drinking also I try to limit the dose to 40 ml at times but he cries wants to drink more like 70 ml same with breastfeeding whenever he is awake at night or day he just continously like to suck till the time he is awake and if I don't he cries I am exhausted as he does this for one or two hours otherwise he cries plz advice what is this thank uu