Help weaning!

Vo

My son is 18 months old and is still breastfeeding pretty much on demand. He can go long periods without me but as soon as he sees me he wants to feed. He does eat 3 meals and drinks milk/juice out of water bottles or just regular cup (I havent found a sippy cup he will use). Hes now aggressive when it comes to wanting to breastfeeding. He has cried for 20 mins straight even with redirecting to come back and still cry for boobie. Anyone have any advice because to be completely honest I didnt plan to breastfeed this long (really only wanted to do it for the first three days but he never took a bottle lol). Also, he will drink his own drink then come to me to feed him. I know it's a comfort thing for the most part.