Hi Gill
As Jean says I have had various problems with low white cell counts and it can become quite a serious issue if not dealt with quickly.
The lower the white cell count, and in particular the neutrophils, the less resistance you will have to infection. I suffered for 5 months last year with ongoing infection and neutropenia which was caused by a reaction to an increased dose of methotrexate (I had been taking it successfully for years prior to this increase). Normally '4.0' is regarded as the lowest acceptable level for the white cell count and 2.9, I would have thought (and in my own experience!) would suggest not proceeding with methotrexate until the count improves. The minimum acceptable level for neutrophils is '2.0', anything less is regarded as Neutropenia. What was your neutrophil count when the WCC was 2.9?
Methotrexate works by inhibiting the activity of the immune system and consequently reducing/slowing down the rate of inflammation. The RA is producing the inflammation that the methotrexate is working to control, so I'm not sure I follow your doctor's thinking!
Lyn x