I'm 11 stone 4, 5ft, currently have a British Bed Company medium 1000 pocket springs mattress on a slatted wooden base which is only 18 months old. This mattress was greatuntil recently, giving good support whilst being nicely cushioned and padded. I have ME/CFS, fibromyalgia and chronic migraine (migraines 80% of time) so am in bed the majority of time, either sitting or (mostly) laying down. This mattress has sunk at the ends so that I feel like I'm laying down hill, which is exacerbating my vertigo and migraines. I think this was caused by a period where I was feeling better and was sitting up more. I ordered a Sleepeezee mattress which has 900 pocket springs, medium but seemed firmer but after a week, it felt like I was laying in a dip and was not supportive enough despite seeming firmer than my original mattress. I feel I need a supportive mattress, maybe 2000 pocket springs but it mustn't be too firm as this can make the fibromyalgia worse. However at the same time I have pain in my joints and back and this needs support. Also the mattress needs to be up to me being in bed 20 hours a day with out sinking in the middle or at the ends. Which mattresses do you think I should consider?