I have considered moving her feed and being flexible, but I don't know how she'd adjust to a change when she's had this routine of a bedtime feed since she was born? I don't understand how I can give her one feed for a few days and then she doesn't feed the next day then does. It seems strange to me that she'd adjust to this? And I have no idea now, what the signals are that she'll give me when she wants milk as we've worked to routine rather than need? If there's advice on this then I'll consider it.
There's also the fact that my fibromyalgia may improve if I stop feeding as it can be tiring for me.
I don't know about the fibromyalgia however you find a new normal each milestone your baby hits. Plus your baby has a different routine with each caregiver. Trust me, it's really not as traumatic for them to adjust to daddy putting them to sleep a different way than it is to be cut from the only comfort they have had. But it sounds like you want to wean, so I assume the answer to my first question is you aren't looking forward to it because you know that it won't be easy for her. My best advice is that you can't do bedtime at all until she is totally weaned. And your cobath should probably stop so she doesn't feel rejected and more in need of comfort.
To answer your questions though, her cues will not change. Nothing at all would change. Other than the fact that you can go out and not pump. Your body will adjust to missing sessions and so will your baby. Your supply may suffer a bit, however since weaning is your ultimate goal, does it really matter? In fact it may help. Perhaps the lack of milk will cause her to reject you instead and then you can wean gently.
I also don't have any experience with fibromyalgia. But babies are really adaptable. You could continue to nurse on the evenings you are together and let things happen in the natural course of things. My guess is that when you do the two weeks when she won't see you at bedtime that she will probably wean on her own. But maybe not. You never know. I thought that my first daughter would wean on her own when the milk went away during pregnancy, but she didn't. However, she was given free access to nurse whenever she wanted up until that point, so it's a really different situation. I have known several women who have gotten their baby down to one nursing session like you have and then gone on a trip and then not nursed their baby when they got back. It seems to work for them. :shrug
I also agree about the bath. That just seems cruel to me to reject her like that in the bath.