Wetting bed nightly AND during naps

L

Our son is 17+ months and every night he fills his diaper with pee and wets the bed / sheets / mattress cover / his outfit. Every. Single. Night. And most nap times. I’m doing 2 loads of laundry a day just in his bedding alone. What can I do to help with this? He isn’t ready for potty training IMO. I hate to limit his milk- he has a sippy of milk before bed and his nap, because it helps him sleep, but is this the problem? Thanks for advice!