You have to make a choice.
1) You co-sleep and keep him in your bed always, feeding on demand, and forget about his crib. You postpone the transition to a much older child going into his bed - and you can search on Mamapedia for people who have been successful with this as well as those who are miserable with a 2 or 3 or 5 year old in the adult bed. An active sleeper can keep Make a plan now on how you will deal with this.
2) You talk to the pediatrician about feeding a child that age in bed and letting milk collect and coat his teeth at night. You are setting yourself up for dental problems for him. Also, you should learn whether a 15 month old needs to eat at night (my pediatrician told me that my 6 month old could go all night without feeding, and he'd make up for it during the day). You will probably learn that he does not need to eat for nutrition, and so he is using a bottle for comfort. So of course, when he wakes up (as all babies and all adults do), he has no idea where he is because he's in a crib and not with you. He needs to go into his crib while he's still slightly awake. He has not learned to self-soothe and to settle himself down. You have to teach him this. I doubt this has anything to do with his teeth. You can talk to the pediatrician or get a book from the library on the Ferber method. Yes, there will be a few nights of difficulty but he will learn to calm down if you do it right.
As things stand now, your baby is not getting deep REM sleep necessary for brain development, and you are a danger to yourself and others if you are driving while sleep-deprived. So the current situation is completely unacceptable for all kinds of reasons.
Please educate yourself on Ferber and on co-sleeping, decide what you are comfortable with now and down the road, and make a more educated decision. Whatever you do, stick with it until it works. Consistency is key, and it's actually very comforting for babies and toddlers to have the same routine.