When should i be concerned about low wbc? i've had my blood tested every 3 months for the past 9 months and every time it's low. next step?

Depends!: It all depends on what is causing low wbc. In certain ethnicities, slightly low WBC is normal. However, i always advice having a full work up including viral studies. The trend of WBC and whether other cell lines are also affected are important deciding factor as well. Low WBC can be due to benign or cancerous causes. I recommend that you check with your doctor for more info.

Low white cells: The decrease in the white blood counts which is chronic means that it is either familial, bone marrow diseases like myelodysplasias, leukemia, lymphomas, or rheumatic diseases such as lupus, or drugs as immunosuppressives, chemotherapeutics, antimalarials, enlarged spleen from chronic liver disease causes low counts also viruses such as HIV CMV hcv and alcoholism.

Give us the actual r: Unless you give us the actual reports with numbers, it is hard to address your question. There is a wide range of WBC over which it can be normal. More importantly, we need to know the differential counts so that we can see the % neutrophils and total neutrophils(anc), the latter being the most critical number which would guide any future interventions for diagnosis and treatment, if necessary.