I bought a 3ft pocket sprung mattress approx 20 years ago. I didn't realize at first that I was supposed to turn it every week and have rather worried about that ever since. I subsequently turned it fairly regularly but this is getting too difficult for me. I am 78 weigh 7st5 and have osteoporosis. Foam mattresses don't appeal - I gave away a new foam pillow once because I couldn't bear it making me keep my head in one part of it. My mattress is comfortable enough and only shows a slight indent from where I sit up on it. Do you advise changing it please and what is less heavy if anything. Would a topper be the solution?