Thank you, Nuby sippy cups!
As a result, I am happy to say that our very distressing strike situation is officially at an end. Thankfully, Leah began taking the bottle last week (shortly after my post, truth be told).
Ironically, I had these sippy cups all along. I bought them a few months ago in preparation for the new adventures in eating and drinking which I knew were in our future. When I tried to give Leah some water from them, though, I discovered that they were a bit too big for her mouth.
So naturally I purchased a few more, none of which she was interested in taking milk from, despite the fact that they were appropriately sized for her mouth.
After we found out how much she likes to take milk from the dropper, I remembered these bigger, stiffer, wider-mouthed sippy cups I had stashed away, and voila!
Thank goodness that is behind us. I don't think I could have felt more terrible and guilty about a situation.