This is the time when milk supply swaps from being hormone driven to being suck-driven. it is completely normal for:
bubs to get fussier and want more milk
boobs to feel floppier
Feed him as often as you can - be willing to cluster feed when you get home - and things will sort themselves out. As long as he is still weeing lots and pooing most days and gaining weight then he's getting enough.
As for the bottle - he's becoming more aware. Can you get him to start sucking on a finger and then swapfor the bottle? Or maybe even feed him with him lying on a cushion on the floor, so it's not in a "booby-style" position?