My daughter turned 16 months old today and I stopped nursing last Saturday. She would nurse before bed and during the night. All I've done is tell her, "'nana' is all gone" and "there's no more" which she understood and for the most part it's been easy. At 13 months old your daughter should understand these words, too, or some form of it. There have been a couple nights where she's gotten upset and really wanted the comfort, but after a minute or so she calmed down and went back to sleep. I've been able to do this even with her sleeping with us. She starts off in her bed, but ends up in ours. I should also point out that she's working on a hard tooth that should break through any day.
I have to admit I'm missing it and I still have quite a bit of milk in one breast. I'm tempted to start up again, but then she's sleeping better (she would some times eat at 3, 5 & 7am). The main reason I've stopped, though, is that I want to get pregnant again and have been trying since September so I'm hoping by weaning her we'll get #2 on the way.
Merry Christmas!