This is a good learning/discussion point: The post common cause of iron deficiency anemia in menstruating females is menorrhagia. Celiac disease is often an acquired disease in later adult hood.

This is not to comment or challenge directly your case but knowing the two above facts it is not uncommon (in fact I have personally seen this in practice) where your above outline is perfectly reasonable.

A woman may have multiple reasons or a sequence of reasons for IDA, developing celiac later in adulthood - it’s totally possible they had chronic blood loss anemia before that.