It took 9 months, a lot of tests, and a 12 day hospital stay to rule out everything else for me. I have it in my peripheral joints so not as simple to diagnose

It took nearly 16 years for me to be properly diagnosed. I was told it was psychiatric ("No one can have this many problems" was the exact quote), fibromyalgia, chronic fatigue syndrome, lack of exercise (I exercised 6 days a week for at least an hour each day), too much exercise, etc.etc.etc.
First, a nurse in my neurologist's office asked if I had ever been diagnosed with multiple sclerosis, and I was horrified. (I found out later that she was fired for making the suggestion, which is awful, because without her, I doubt I would have ever been properly diagnosed!) But her comment made me think about autoimmune ... I talked to my endocrinologist, who lit up like a bulb, ran some blood tests and sent me to an immunologist. The immunologist discovered that I had an immune deficiency, began treating me for that, then sent me to the ninth rheumatologist I'd seen (but she knew him well and assured me that he was wonderful - she was right).
That rheumatologist took the time to actually listen. Rather than slapping a label (fibromyalgia and chronic fatigue syndrome are the catch-alls, especially for female patients), my rheumatologist asked intelligent questions about my history (note: if they have a checklist and only allow you to answer yes or no to their questions, move on). He ordered an ultrasound of my hands, X-rays, an MRI, and blood tests, and he actually read my stack of medical records. He ran a test for HLA B27, which was negative, but it didn't deter him. He started with conservative treatment, and when I had a mildly positive response, we continued on. I will always, always be so grateful to him and to my entire team.
Just don't give up, and don't be afraid to find the doctor or doctors who respect you, listen to you, and give you options.

Same mri of pelvis after 30 yrs blaming one rheumatoid arthritis
Also blood work for Hla b 27

I was finally diagnosed by mri of my sacroiliiac joints. Doctors go by inflammation markers in your blood and the gene test HLA-B27. Also family history. But mostly symptoms, I think. But there is no specific tests to diagnose it. Also, other areas of pain like plantar fasciitis, achilles tendon pain, other joint pain, gut issues, rashes and uveitis. All this helps paint a picture for a diagnosis.
My blood was normal because I was already on ibuprofen. My rheumy said normal blood work is not uncommon. My CRP was elevated in the past.
Have you been diagnosed with Fibro? It took me 20 years of pain to get off the fibro. merry-go-round.
I hope I helped and good luck.