Fellow Fibro here, albeit somewhat older than you.
Re your indigestion - I had it quite severely too. The best thing my GP did was suggest I try the FODMAP diet, look it up on google. Within a few days my digestive system felt better than it had for years. I still follow it, and it has contributed to my well being in so many ways.And yes, you CAN have honey with it. So maybe give it a go? Gaviscon has never been seen in my home since!
I also found gluten, dairy, sugar and soya a major problem, but with all the recipes there are for food/meals now, it wasn't a problem. Even though Gluten free bread made me ill too, I found a fab recipe for flat bread which takes 5 mins to make and its perfect. Even though your coeliac test was negative, you could possibly be intolerant to it, as am I.
Excercise - Please, please keep this up. I was fine until I got through the menopause then came up against major problems with my muscles. I sit down a lot in my work and caused a lot of trouble with major muscles in my back and upper legs. I have now adjusted things so that I can stand to work as much as possible, (this keeps me straightened out and those muscles working), then sit down for a break, then short walk around the garden, then back to work etc. Keep those muscles working as much as you can - but gently.
Sort yourself some simple stretching exercises and start to do them NOW. One rep per exercise per day to start with is good, and build up as you can.
Walk every day if you can - doesn't have to be far, but try to establish a short route to begin with. Once you can easily do that, add on maybe another 50 ft. per week/month, whatever feels right for you. You say your calves ache, so start them off on a gently slope, and be kind to them afterwards with a massage and maybe rest them the next day
I can now walk over a mile a day on my good days, and climb a pretty steep hill near where I am. On my lesser days I drop it to half that, and on bad days I don't do it.
Massage your arms, legs, wherever it hurts. I know it may hurt to massage, but it's hurting because the tendons are tight. Do it regularly, and the pain will lessen, and you may feel able to do more.
With all of this, the temptation is to stop once you feel good, but don't, keep it up - though of course if you have a bad day or few days, then of course stop and rest. But don't let those few days slide into weeks and months.
You say you get achy on the sofa or sat at a desk - fibro hates the same position for more than a few milii seconds! So I break up my day into bite size pieces. Eg work a bit, rest a bit, repeat. Go out for a walk, rest some more, work some more, etc.
Like you I had major stress in my life which I've now removed myself from, and it has helped enormously.
So be kind to yourself. Listen to what your body tells you. Feed it what it needs, not what it wants (in my case chocolate) Rest when you need to, but exercise when you can. Enjoy the small things. and yes, live life to the full your way