Gave up bottles at 8 months. (he was ff from 5 days old)
DS used to bloody love his bottles, had 8 ounces every 4 hours at the least, sometimes I'd have to make up more and he'd have up to 10 oz! He also fed to sleep for all naps and at night.
He got a horrible stomach bug at 8 months and didn't have any milk at all for almost a week.
Just never bothered going back to bottles, he never cried for them so didn't seem any point to give them back to him only to wean off 4 months later. He was already drinking water from a beaker anyway so I think the bottle was just for comfort.
If he cried for milk I still gave it to him but he just drank it out of a beaker himself instead. Turns out he didn't give a crap if I cradled him and stared lovingly into his eyes, he just wanted the milk!
He honestly never again wanted a bottle.
Switched to cow's milk at 12 months to the day as I'd run out of formula on that very day so thought I'd give it a go. He didn't flinch.
I'd never heated his formula any higher than room temperature anyway and started giving it to him straight from the fridge at about 6 months as he was just so bloody loud when he was hungry.
Since then he's just had milk when he's asked for it. He's 14 months now and gets through probably 2 or 3 beakers a day but rarely drinks one all at once, just sips here and there. I find it bizarre as he's exactly the same with water but is very definite about which one he wants at which time 
He doesn't have morning or bedtime milk at all, hasn't asked for it since he stopped having bottles.