FTM and I’m clueless right now please help😫

I have a 4 month old. Ever since I brought him home from the hospital he has wanted to eat every 2 hours the only difference now is that instead of 2 ounces he drinks 3. He will not drink more than 3 and he sometimes won’t even drink all of that. Idk what to do. He’s gaining weight fine I think but everything I’ve read says that a 4 month old should be eating 4-6 ounces every 3-4 hours. My sister in laws baby is just a month old and is eating 4 ounces! Im so confused and worried and honestly annoyed because with him eating like a newborn and sleeping like one too I can’t get out of the house to do anything and I’m going crazy!