He's likely okay. If he's getting enough to drink then you shouldn't be worried.
Babies start wetting less and less the older they get.
When he was a newborn he would need at least 10 or 15 diaper changes a day.
But it's very normal for the number of diapers to decrease the older the toddler/baby gets.
If you're still worried, you might take him to his pediatrician just to be safe.