That's weird, making Nat send the photo plus following her later that day should trigger the dom events. Let's just say you still get drugged but Andrea gets what's coming for her in that one. Not sure why it isn't triggering for you.
Assuming you don't mind spoilers, with the dom path instead of making Milly passive it makes her aggressive. They go back to Andrea's house and she screws her a couple times. Milly tells Andrea at the end that she owns her now (paraphrasing). I definitely prefer this one over the sub, which was still good but made me a little uncomfortable with how it went down.