Anaemia could be one of the reasons for your symptoms of tiredness,light headedness,fainting attacks depending on the hemoglobin
your doctor needs to decide whether you would benefit from oral iron supplementation or injectable iron. Or need a blood transfusion
if anaemia is severe.
Get other blood test
done to rule out other causes of anemia.
Dialated left atrium can be if you were having ny previous heart diseases which was unknown but exacerbated in pregnancy,or due to cardiomyopathy
of pregnancy but that is least likely as cardiomyopathy does not manifest at 6 months of pregnancy.