trying to figure out a 5 month old schedule.. please help before I lose my mind!!

So my baby is waking every 2 hours at night. Not to always eat..  
He naps about 3x a day for a lot 45 mins to 2 hours.
He's asleep by 7pm and up at 6/630am. 
I tried just letting him sleep and not get him back down when he wakes up at nap but he was miserable all day. And slept horrible at night. 
He has a bedtime routine and pretty consistent nap times. I'm just trying to figures out what I'm doing wrong. 
I read that 5 month olds need 3 naps and an be up from an hour to2 between naps. And sleep a total of 14 hours a day. Which seems completely impossible. 
His last nap is from 4pm-5 or 530pm. By then he's already napped 4 hours during the day but I put him to bed by 7 to avoid him being over tired.
So do I keep him awake longer before bed? Or does he wake up earlier? 
I feel like it's mathematically impossible to have him nap 3x, sleep 14 hours during the day and keep him from being overtired.
But something needs to change. I can't not sleep.
Please help!! 

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