I'm still learning more about RA - one of the newer tests that doctors use for RA diagnosis is called Anti-cyclic citrullinated peptide (anti-CCP). This test is based on blood work - it is used in conjunction with Xrays and physical symptoms for diagnosis i.e. a positive Anti-CCP result is not the sole indicator of RA.
Your doctor may do that test too for enabling diagnosis (my PCP did before sending me to the Rheumatologist). That is part of in-depth blood work.
I know RA is quite frustrating - from all the blood work, X-rays, to tests and not to mention, all the pain and joint swelling.
Hang in there, hope you find relief soon.