Fibromyalgia & mostly bedridden

Can you, please, make any specific suggestions for one of your mattresses for someone like me. I warn you, it's complicated! (Sorry: long message follows.)
I have a severe form of fibromyalgia/chronic fatigue syndrome and at times find almost any surface painful to lie on. For example, when staying in an hotel or visiting friends I often end up having to lie on pillows on top of the mattress in order to be able to sleep.
In addition, because fibromyalgia can also affect the brain's sleep (in addition to loss of sleep because of pain) I also have a very disturbed sleep pattern meaning I can often be asleep for up to 16-18 hours at a time (and/or awake for up to around 30 hours instead.) When I am awake I still mostly have to stay in bed just recovering from the bouts of pain, and because of the chronic fatigue problems.
And to add to my joys, I also have very frequent migraines. Fortunately the migraines are relatively mild but nevertheless I rarely go a week without at least one needing me to take to my bed, and I often spend weeks or even months at a time with a migraine (at some level or other) every single day. This means even more time spent in bed.
The upshot of all this is that I'm more or less bed bound for weeks or sometimes months at a time. (I'm a bundle of laughs, me!)
I realise that all the above means it would be ridiculous to imagine I could be comfortable in a cheap bed. On the other hand as my husband and I are pensioners (I have only the minimum state pension) we can't afford (much as we'd like to!) a bed at the sort of 'luxury' prices charged by some retailers. However we are able to consider buying one of your more top-end beds, but need to be sure that if we do make such a costly (to us) investment, we have chosen the right bed for our specific and complex needs.
Just to pile difficulty upon difficulty, I still have menopausal problems and need a large fan permanently by my bed, winter and summer alike. So I'd prefer to avoid memory foam because of over-heating issues. (I currently use a memory foam topper to help with cushioning, but am aware that it adds to my over-heating.)
Lastly, can any of your mattresses be used on an adjustable bed? (I spend so,much time watching tv in bed that I'm considering uying one (despite concerns about the slats) because an adjustable bed might help redistribute my weight away from my most painful places.) What are your views on such beds?
So, after all this deluge of info, what can you suggest, please?
I am 5''5" and weigh around 16st (not a lot of exercise possible with my health problems and eating is one of my few remaining pleasures ☹️) and my husband is 6' and weighs around 13 stone.
I understand that this means a medium spring would normally be the first choice but I am nervous that there would not be enough 'give' to fully cushion my aching body, particularly in the points of most pain (in my case buttocks, top of thighs and shoulders). I find most mattresses just don't allow me to sink in enough to assuage my pains. Even with an extra thick memory foam topper on my existing mattress I find it uncomfortable at times. (The mattress itself is elderly — about 15 years — but was a top-of-the-range mattress with latex (I think?) from Habitat. It's still going strong, no dips or sags, but we need to replace it to meet my current and future needs.) I suppose, really, I'm looking for reassurance that a medium spring, based on my height and weight, would also take account of my pain problems, and that sufficient cushioning from the upholstery could meet my needs.
If you are able to make a recommendation taking my particular (and complex) needs into account I will be happy to be guided by you. Thank you for just reading this far!
Regards,
Aileen
P.S. Yours is the only website I have been able to find that actually explains the varying materials in beds, and how they work. I now feel much more able to make an informed decision before making this expensive purchase. Thank you so much for that. Until I found your site I've felt as though I was about to throw possibly thousands of pounds into a sort of fog, with no clear idea what might eventually loom out of it, how that might meet my needs, or the real value of what I might be getting. Whether we eventually do decide to buy from you or not, I will be delighted to refer friends and family to you in future for your honesty and clarity.