Diagnosing rheumatoid arthritis is a clinical diagnosis.  While there are blood tests and imaging (including x-rays, ultrasound or MRI) which can be helpful to make the diagnosis, it is possible to make a diagnosis even when all these tests come back normal/negative.  Your story and physical exam are critical and should not be ignored.  Having a referral to the rheumatology team to listen to your story and determine a diagnosis is a great next step.