Low white blood cell count

I have had an extremely low white blood cell count for years now with my lowest being .8. I have been to hematologists and an oncologist who did a bone marrow biopsy but have gotten no answers. I eat pretty healthily and take a multivitamin and I rarely get sick. I have developed allergies as a result of having a low white blood cell count but other than that no issues that I am aware of. This still weighs heavily on my mind just not knowing what is causing this. I wonder if this makes me more susceptible to cancer and any other dreadful disorders. If anyone out there has any tips on how to raise my white blood cell count I would love to know or any knowledge of this disorder at all would be appreciated