I guess, sometime between when HKS helped her into the bathroom that morning, and before they all returned to the suite at 12:00 or whatever it was, ANS got up (since she was so strong and controlling at that point) and went into the other guest room and took some more pills or the liquid chloral hydrate...
If it's true that she would have had to have taken more medication...
Howard has said that he didn't see her take any meds. So, if he didn't give them to her and he was the only one to interract with her the day she died...we'd have to believe that she went into the guestroom on her own and helped herself to more medication and then made it back to bed. Quite a trick if she couldn't make it to the bathroom on her own.