Dragonfly, I know how it feels when they wean before you are ready. I hope you are doing ok.

It's not usually recommended that they have cow's milk as their main drink until 1 yo. Maybe this is why he's not keen on it, he just might not be ready. Instead of milk, he can drink water and get the nutrients from his food. Green leafy vegetables, sesame seeds, and a variety of other foods contain calcium. Also if he is eating cheese and yoghurt and having milk on cereal that can go a long way to meeting his daily requirement.

If you are worried that he's not eating enough of the right foods, there are vitamin supplement drops for infants. They can make up for any short fall and can also stimulate the appetite for fussy eaters. There are also paediatric dieticians who can help you with an eating plan if you think you need it. But it sounds to me like you are doing a great job.