how does this work? So I'm breastfeeding and throughout the day he eats every hour and half to two…

how does this work?

So I'm breastfeeding and throughout the day he eats every hour and half to two hours for fifteen minutes or a half hour or somewhere in between. Then starts what I guess is called cluster feeding towards night time. He went three hours without eating, I woke him up to try and feed him, he only ate five minutes and is back to sleeping. Should I be trying to make him finish eating or just let him do what he wants? He's a week old. Also, it hurts pretty bad, would it be too early to pump afterward what he doesn't finish or could that mess up the feeding situation? I'm so clueless bc I didn't make it this far with my first so I need everything dumbed down. I literally had to Google what engorgement means.