Regardless of your blood work, "numbness" is not a sign of RA - it is a sign of MS.  You need to see a neurologist. I have a cousin with this, and my sister was just diagnosed with it.  She is experiencing numbness in various limbs, and has a small lesion on her neck.  When the body attacks the myelin sheath around the nerves, it interrupts the transmission of the neurons through the nerves.  It is reversible, if you catch it soon enough. The drugs can be quite an issue, and both relatives, were Type A energetic types, and have lost most of their energy.  They both keep up the work outs, faithfully, and my cousin who has had it 10 years is doing extremely well. My sister is still working things out.  When an autoimmune disease attacks your body, you will feel tired.  Don't let the docs put you off.  Demand help - research MS - only you know your symptoms, but it is definitely a good direction to start in.  Then push those doctors.  They use methotrexate for MS, which so many people are scared of.  I have been on it for 10 years - and other than a slightly elevated ALT, have had no side effects.  It is a cancer drug, but they take it in grams, not 25mg, like auto-immune people do, so don't worry about side effects. You just have to take folic acid every day - not a big deal. 

I don't know much about interferon, I have heard it works well for some, not for others, lots of side effects maybe?  For me, anything is better than seeing my body crumble in front of me.  Good luck in finding a diagnosis.