@Greyandrare123 I read your post in the waiting room and now have time to post.
I can completely understand the feelings you deal with. You have invisible disabilities and it can be very hard indeed to communicate your needs and have them understood. Especially with fatigue and pain - I truly think that until someone has actually experienced chronic levels of that they really cannot understand.
I recognise so much of what you describe, the overwhelm, the stress around commitment. You need predictability in order to manage your conditions and actually relax.
It's like living on a very low financial budget where any extra physical unplanned exertion costs and undisclosed sum of money more and so you risk going into debt, when you already live in your overdraft.
So no, none of your feelings about this are unreasonable at all. you clearly have found a holiday that blissfully suits you and you need. You also have done the same with work (I work 2 days due to previous chronic health issues which are ironically now a lot better and was close to thinking about upping hours till this popped up 🙄.)
Because I am an accommodating people pleaser Ill end up going along with the suggestions and feel drained and exhausted.
This is where I both also FULLY get it and where I would gently challenge you - from all my own experience.
I've learnt that you have to set some firm boundaries and gentle boundaries. She doesn't fully understand hence the suggestions, but I bet she wants to understand and she's just being polite and offering.
Could you reconsider your place - it's your holiday after all, designed for you and you deserve it the most.
Ideas - Ask Dh to gently communicate that there's a number of things you know you can do on holiday which you're keen to share with them, or do by yourself.
Or, Send a message to her saying "hey, I'm looking forward to the holiday, I'm limited by wonky spine so this is a list of what I do to relax and pace while there; you're very welcome to join me or go off exploring as it's such a beautiful place."
Your firm boundary is that this is your holiday and you're going to be saying no to anything that you can't or don't want to do. (And ear plugs for sleep, set evening dinner times if that helps you etc). Another firm boundary might be what you will do by yourself. Perhaps they'll go out for the day and you will rest at home doing your thing?
Your gentle boundaries are sharing what you will do with her, getting in first so to speak. Invite her to share your walks etc , and suggest more challenging options she could do and maybe you meet at a pub for cake afterwards.
I just think you should go and use this as a time to work on that people pleasing bit of you that's actually slight self sabotaging (I think it's been described as an inner Beryl on mn before.)
<disclaimer: I've been there and have the T shirt, the mug and the coaster>