I second the other ladies. Even under 500ml of breast milk is giving almost 40% requirement of calcium at this age, more if she is drinking more than that. Cows milk is an option not a necessity. Cheese & Yogurt are options for extra dairy calcium and there are lots of non-dairy sources too. If you really want her to take cows milk from a cup or to wean her onto cows milk you could try adding a dash to her water, then a little more next time, and so on to try and accustom her to the taste.