i didnt experience but have heard that happening to lots of parents, esp boys. are you sure everything is aimed in the right direction? you could try the larger huggies overnights, they work great. maybe try both his size and the next, if the size is too big, it doesnt always cinched snug enough to his skin and then will leak as well.
also get some of those ultimate crib sheets. they are waterproof with material over them and snap to the rails in the crib. in the middle of the night, you just pull that off. they are the nicest imo, very well made and when walking into the room, the side of the mattress is still whatever cute sheet you have.
i cloth diaper now, but a good idea even for you to look into is a wool cover over his diaper. wool interlock normally goes over cloth and when the diaper underneath is all damp, the outside of the wool still feels dry, he could wear it alone over the diaper or under his pjs. its antimicrobal and doesnt smell, and very breathable. you only have to wash it with woolwash about every 1-2 weeks. also fleece is a cheaper option. just make sure its not microfleece. its not hot either as my daughter wears fleece and wool over her diapers all summer long. fleece isnt as good as the wool, but still it keeps the wetness from getting to his pjs. i cant imagine with an overnight diaper and a cover . message me if you need any more info for a cover, but check out his aim as that happened to my sister for awhile with her son. good luck!!!
ETA AND WHATEVER YOU DO, DONT LIMIT HIS FORMULA/BREASTMILK. HE IS A BABY, THATS SOMETHING YOU WOULD DO WITH AN OLDER CHILD WHO WETS THE BED. DEHYDRATION IS VERY SERIOUS, AS IS NOT GETTING ENOUGH CALORIES. TAKE CARE.