Anaemia (particularly Iron deficiency anaemia) is commonly associated with hypothyroidism.
However discordance between severe anemia in normothyroid status needs to be assessed. May I request if you could answer following questions in order to help reach the cause of anaemia in your case
How long has your
thyroid status been normal?
Are you pure vegan/vegetarian by diet?
Do you frequently suffer with diarrhoea or loose stools?
Do you suffer with heavy menstrual bleeding?
How many days your periods last?
Next Steps
You would require a careful history taking through physical examination and appropriate laboratory investigation like repeat
thyroid function test, anti-thyroid antibody, full blood count along with peripheral blood film, red cell indices and iron profile.