How often should my 8 month old be nursing?

I'm adding a second meal time into his daily routine (haven't decided on lunch or breakfast yet) and I'm just not sure how often to nurse. We've been on the every 3 hr schedule for so long. Lately hes been going 4 or more hours between feedings and doesn't seem hungry at all in between like he used to. He doesn't sleep through the night so he's still nursing every 3 hours all night. I guess my question is, if he's not hungry should I still offer every 3 hours? My inner panic button goes off if I realize I haven't nursed him in 4 or 5 hours lol.