Eating small amounts

Emily

My boy is 15 weeks old and is still only drinking 3-4oz of formula every 2/3hrs. Some day’s, like today he has only had 590ml for the whole day so I’m worried that he’s not drinking enough. He goes to bed at 8pm and sleeps through until 5:30/6am so he’s obviously content. He’s also showing a healthy weight gain but I can seem to stop worrying about the amount he is getting.

Does anyone else have this?