Kaz, my mother suffers from heamochromotosis, and I have the defective gene that causes it, though thus far my iron levels have been fine. It is a manageable disorder, and my Mum has no trouble dealing with it, and hopefully if I end up the same way, I won't either.
Have you tried to talk to your doctor about hitting the wall at week 3? There may be something underlying that is causing this that he/she can help you with.
Reach for the moon, at least you'll land among the stars.