I was just looking for other info; because you probably don't have anemia or you would know it. I did long ago. That's why I thought of causes of iron deficiency. You can be deficient without anemia. I'm truly not trying to insult your intelligence.
Hydrochloric acid produced by the stomach improves the absorption of non-heme iron from food and supplements. HV has good advice on increasing the stomach acid. You are much younger than me and may not have to worry about the acid; but it would be worth trying the bitters, TMG, etc. that HV recommends for a while. Then test again. Just in case.