Hi and welcome to the board,
I have had joint pain and swelling for over a year now, and I still have a negative RF test. Mine was right at 40. It's my understanding that anything under 60 is condsidered negative. Although I could be wrong. Once you get into see your Rhumy, he will order the complete panel. However, many (if they are good) will treat your symptoms regardless of your test results. I hope this will be the case for you!
I know it is true that when I push myself and get rundown, my flares are worse. Try to rest when you can, although it can be difficult to do.
Good luck to you