I also self diagnosed after years of being dismissed by my GP. My own research (in the very early days of the internet), finally revealed that my symptoms fully lined up with AS. My symptoms were worse in the mornings and relieved with activity (once I battled through the pain), only to be worse after I then cooled down. Just getting out of bed was painful. Most of my pain was in my hips and ribs. I also didn't have eye problems. I would get horrible spasms in my ribs that would even make breathing painful at times (intercostal neuralgia).
A rheumatologists then confirmed the AS, which was now almost 20 years ago. My rheumy put me on Enbrel, which worked wondrously until it turned out to be causing me a lot of nerve damage after 4 years. Sulfasalazine turned out just to upset my stomach, I had little recourse. The pain was even worse than before Enbrel. That's when I tried the low-starch diet, which reduced the pain levels and made life worthwhile again.
Keep in mind that what works for one person may not work for all. I have not had any problems with carrots (in moderation), but other root crops do cause me problems. The low or no-starch diet requires a lot of trial and error. I took about a year to find out what all affected me. At first, my diet was quite bland and disheartening. I then figured out that almond and coconut flour could be used to make many baked goods that I had been missing. Almond, pecans, and walnuts all seem to be fine. Those are not actually nuts but drupes, which are low in starch content.
AS symptoms started 1991. Official dx in 2006 with HLA-B27+, fused SIJ, bone spurs in back, extreme rib/hip pain, and other family with SpA. Started Enbrel in 2006 with good results, but stopped in 2010 due to nerve damage (MS) from it. Getting good results with no-starch diet since 2011.