I night weaned at 14 months to TTC. We ended up having to feed him bananas in the night till over 18 months.
DS could not settle on his own (and it took hours for him to relax and go to sleep) until he was over 2. So we just hung in there sitting and lying with him every night. He woudl cuddle to sleep again during the night (after a banana or some water)
i would suggest if she's been sick or teething that you delay your weaning plans till she's well. IT'll be much easier for you both that way