Im fairly new to my RA diagnosis also but from what ive learned you can test negative for rf or rheumatoid factor and still have RA. My DR. tested me with anti ccp test (FOR INFLAMATION) after checking my RF (rheumatoid factor) which was slighty elevated at 28 my ccp was 101 from what i have gathered is a common test now to " confirm" RA after testing for rf factor. so you might ask to have this blood test run. I believe its called sero-negative if you dont have rf_factor but test positive for inflamation or anti- ccp test.
If im not right on this im sure someone will step up and let you know. I hope this helps some.