Hi OP, in a similar boat here. I was told at 31 week midwife appointment that my 28 weeks blood tests showed 25% drop in haemoglobin! I was so shocked that I forgot to be furious that no one had bothered to call me to let me know the results. I had put the tiredness, faintness etc down to the heat. ...
Anyway, I find ferrous sulphate tablets (which doctors usually prescribe) are quite literally a cork for me, so hideously constipating, and don't work fast enough. I tend to be on the anaemic side in general, so have experimented. Nor can I stomach Spatone.
A friend recommended Ferroglobin to me (Holland & Barrett sell it), safe in pregnancy, like Floradix but stronger. I have been on it for 10 days and definitely feel the difference. I am taking the liquid.
As others have said, it is a case of try it and see how your body responds.
With iron, you need to be aware that the absorption of the iron is really impacted by what you eat with the supplement - vitamin C helps iron absorption, dairy products hinder. I have found that if I take the iron supplement as soon as I wake up and then don't eat for 2 hours that it works faster. But that is me.
Hope that helps! Good luck.