LO is nursing constantly - help!!!

My LO is 15 days old and the last few days he wants to nurse CONSTANTLY. I mean continuous nursing for like 3 hour stretches with only intermittent breaks lasting a few minutes. It has become so draining emotionally and physically to not be able to do anything but nurse him. I don't think he's drinking the entire time because my breasts still feel somewhat full and I don't hear constant swallows. He gets lazy and just suckles so I unlatch him and then he gets upset and I know he's still hungry so I put him back on the boob and I get a few minutes of swallows but then he's back to suckling and gets sleepy. What do I do to get him to focus on drinking when he's at the boob and not just suckle for comfort? I can't be nursing for 3 hour stretches numerous times a day. I'm also able to pump 8 oz combined after these marathon nursing sessions so I know it's not an issue with my supply. Help! I'm losing my mind!