Maybe you don't have AS?
Do you have ANY daily pain?
Maybe you're just lucky?
I didn't notice a difference with what I ate BEFORE I started the NSD. FOR YEARS I HAVE BEEN IN PAIN ALL THE TIME - SOME DAYS WORSE THAN OTHERS!!!
Then I started the NSD (slightly skeptical, as I am HLA B27 -ve...), and over the months I have LOST or SIGNIFICANTLY REDUCED the pain in many areas - my SIJs, back, thoracic spine and ribs, feet, neck...some days these past couple of months I have had NO PAIN in my SIJs - MIRACULOUS!!!
9 months into this, I am still getting better,

and am still getting episodes of worse pain when I think I can cheat...

I think you need to try the STRICT NSD for 6 months before you decide that your life CAN'T be improved by it!
You may never know what benefits it can give you if you never try for yourself,
All the Best,