What you are describing I am going through now. But I know it's tied to the Seasonal Affective Disorder and thought, "But wait! She's in OZ. It's spring!" So I read on to see what was up.
I've never been dx'd with low iron, even after the millions of tests done over the years. I know my SADS is directly related to the time of year and to the fact it's been raining at least every 3 days with constant cloud cover between. (I have atypical SADS, too much cloud cover can bring it on....)
Good you made the connection and have the tools to alleviate it. :))