I had a blood and mucous free kind of remission for about
7 years on virtually no meds (asacol made me tired and gave me wind). Tended to have urgency a bit in the mornings and lots of wind in the mornings which went when I cut out multigrain bread. I'd have wind at night too, dry wind though, no passing of b&m with them, which was great
. I don't think I was fully in remission as always had a raised ESR and a private stool test showed raised lactoferrin (another marker like calprotectin).
One day the blood and mucous returned out of the blue, possibly I'd eaten a bad ice cream, one that had been melted and re-frozen but I am really not sure what triggered it. Meds then cleared it up for me for another 3 years and I did stay on Lialda then.
Interesting that your stools are more formed with a plant based diet, mine would be less as more fibre made me looser.
I think a colonoscopy is the only way to tell if you are in remission. You could have a calprotectin test to see if you have any inflammation.