If he is nursing 3-4 times during the night it’s for comfort not for hunger. So you need to sleep train him. Either try reducing one session at a time or drop all of them, whichever you think would work best. He is old enough to successfully sleep train. You can still nurse during the day, it’s not an all or nothing type of thing. Many breastfed babies sleep thru the night and still nurse during the day. Please don’t give up breastfeeding because you think he is too attached. Trust me, when it ends you will miss it.