WBC is 2.91. What can I do about this?

Based on this low WBC you should need to have hematology clearance prior to any elective surgical procedure.

I think that your plastic surgeons plan is good one.  If the values remain low, a hematologic work up is indicated. There is likely nothing specific that you can do to make the value normal.  

 I'm sorry to hear about the abnormal lab finding;  this must be stressful as you plan your procedures. I think that you and your plastic surgeon have a good plan;  determining the cause of the low white blood count will be important. Sorry that I do not have any specific recommendations as to what "you can do to make it normal" (much will depend on the cause of the leukopenia). Best wishes.