Your Hemoglobin is  low (n=12-16)hence possibility of blood loss Menstrual bleed or Gastrointestinal bleed 'hemorrhoids or hook worm infestation or malnutrition common causes. Do a peripheral smear ESR ferritin and stool occult blood test. If iron deficiency can take medicine If not improving need evaluation for blood loss. A USG abdomen is also useful. First find out cause for blood loss.

Hemoglobin is really low. Is there any history of heavy mentrual blood flow?

According to report your hemoglobin is really low.. you will require medications orally or through iv accordingly.