What does it mean if you have always had a high wbc count like11-12 and then one day it is 16 with no signs of feeling sick. could this be a leukemia.

Need to examine: At a minimum it would require examination of peripheral blood smear by a pathologist and depending on the findings, additional investigation may be needed. You should discuss the matter with the doctor who ordered the blood cell counts.

Could be, or: Could be not, other causes for increased WBC count include infections, drug effects, stress or inflammatory disorders. Clinical context is important too, the counts are high, no doubt, but have to be put in perspective, why are you checking those counts in the first place? You need to follow up with your doctor who may refer you to a hematologist, best wishes