Do lots of people get anemia, or is it unusual?

Not uncommon. There are many causes for anemia--blood loss, iron or vitamin deficiencies, chronic diseases and cancers so it is not an uncommon problem. It is important to find out what is causing the anemia so that it can be corrected.
Common. Anemia is low blood count and may be mild or serious. Either you body does not produce enough red cells (blood cell cancer, uremia, chemotherapy, low iron, malnutrition) or you are actively bleeding (ulcers, trauma, GI malignancy, gu malignancy) or you are destroying your cells (inherited, splenic overactivity). Your hematologist needs to sort this out. If the cause is gone, you can do well.