thats ok, ive always got low iron, with my daughter, the midwives were amazed i was able to walk arround, and i was always getting told off for not taking my iron pills every midwife check (i was, they just wernt working!) as my iron was dropping so low each time they were convinced i wasnt taking them!!
hope this helps and you feel better soon, i have to go the chemist and get ones with a higher content again, as the ones im on now are having no effect, again!! (and its still only early days yet, oh fun!!)