I just cringe when I see a child over the age of 12 months drinking from a bottle.
There are so many reasons that it is wrong for a child over 12 months to be drinking from a bottle. For one it can delay a child's speech, it has to do with how the tongue comes around the nipple of the bottle in order to suck from it. This cause the child not to know how to place there tongue flat in order to produce certain sounds.
Another reason it is bad is because it can interfere with how the child's teeth come in, especially if the child is going to bed with the bottle. It can cause tooth decay or weak teeth if all the sugar from the milk or juice is left on there teeth or gums while they sleep.
I feel the most important reason is that a child would most likely end up drinking most of their calories from milk and not eating enough food. Which places the child at risk for anemia and other nutrient deficiencies.
I always here from parents that it is just to hard to that it away. Atypical developing child should be able to transition fairly easily from a bottle to a sippy cup. The process should start around 6 months. While the child is starting with solid foods, you should also introduce the sippy cup with water or juice with no sugar added ( no more than 4 ounces per day). I don't expect them to start drinking from it right away. At first they will probably bang it on the tray. To help them you can tip it up to there month, they probably won't know how to suck from it at first but keep giving it to them to play with and get familiar with it. This way when they become a year it will be easy just to get rid of the bottle. They have been using it to drink water and juice out of it for the past 6 months. Never put water or juice in a bottle. There may be times when you need to give a child under the age of 6 months water and juice and in those circumstances it is okay. So when it comes time to transition you just put the milk in the sippy cup, never put regular milk in a bottle, it makes the transition harder.
If they refuse to drink the regular milk, don't worry. Do not breakdown and put it in the bottle because you are afraid they won't get enough dairy. That is what they are waiting for. It is the game, they want to see how long they can hold out before you will give them the bottle back. Now that they are a year they don't need as much milk. They should be getting most of the nutrients that they need from food. Dairy is important, but is not the main source all their nutrition. They only need 12 ounces of milk per day, and they can get all they need from yogurt and cheese. One and a half ounces of natural cheese is the equivalent to 8 ounces of milk. You can also give them kale or broccoli, which a good sources of calcium.
If the child refuse to drink milk from the sippy cup in the beginning, I would try an open cup that you can hold for them or putting a sippy cup with milk on their tray during meals and if they won't drink it then after the meal I would offer water to them.
I know it is a hard thing to do, because you feel like you are depriving them. In the long run it is the best thing you can do for them. Good Luck and Stay Strong!