My DS was having 8-10 at that age.
By 15-16 months he was down to 4 or so after we night weaned at 14 months. He dropped the day feeds more or less by himself.

If you drop feeds, there's no need to give him a bottle at all. You can offer some milk (maybe in a cup) - whatever kind you prefer - but no need for formula, especially if he is eating well otherwise. Don't replace all the feeds with milk as this may fill him up to much and affect his eating. Although he's feeding very often now, he will be regulating his total breastmilk intake appropriately (if that makes sense) and if you give bottles of milk to replace these feeds you may end up giving much more.
I'd go for whichever feed you feel he is least interested in first - try distraction and offering drink/food. Do it gradually to avoid any lumpy problems. The ABA will also be able to offer some support and guidance for droping feeds.

More generally, maybe try and get yourself a break. Just getting some 'me time' without your son might make all the difference to you, even if you continue feeding.

Good luck!