Might be a stupid question but gave you tried giving him milk in a normal cup - no spout or straw. It's a tricky one because there is no issue with a bf baby wanting to nurse for comfort at that age, but all kinds of pressure on bottle fed babies to not be ruining their teeth with bottles, but psychologically the babies have the same needs!
He's relatively decent at trying to drink from a regular cup. He'll steal sips off whatever we have, but he's not exactly the most coordinated dude handling them on his own. I AM seriously concerned about his teeth since he's taken to copying his cousin on fighting the toothbrush when he used to love it, especially if I sat there and just brushed his tongue for awhile.
I totally get the double standard too. So difficult.