What's your position on continuing to BF? Have you decided you definitely want to stop now/within 4 wks?
Your LO is 12 months now, or close to, yes? You could drop the day time BFs (mid morning and mid afternoon) now really by switching to a solids snack and a drink of water. Although you don't want milk intake to drop to zero as they do still need dairy, they also don't need the same amount they've been having since they were babies, yk?
Personally I found mine could not take milk fast enough from a sippy to keep him satisfied so whilst it was fine to switch to a small sippy of milk with a solids supper when dropping the BT feed it was not fine for the big milk drink at WU. I think quite a few LOs are older before they can really guzzle milk from a sippy.
The straw was a success here for the WU milk although it took a month to really make the switch.
Otherwise (and if you cannot/choose not to continue to BF and need some milk intake from other sources) I'd make up the quantity in solids, yoghurt, milk puddings, cheese, cheese/white sauce, add milk powder to any recipes you can (eg if you make pancakes make with milk but also add a few tables spoons of milk powder which is fortified with vits too), maybe give evaporated milk a go (it has if I remember rightly about double the calcium of regular full fat cows milk) it is not sweetened just thicker and creamier than milk.