Hi Ferlew,
You are not getting the best service from your doctor are you? You have obviously been checked over for "leaks", and none found.
Without too much detail, I am not a doctor, so what I say has to be taken with caution. As mentioned earlier, it is possible your body is not processing your iron intake correctly-malabsortion. Roughly speaking your body needs between 14 to 18mg iron intake daily from all sources. dependant on age and sex.I have a daughter who is on 120mg tablets per day, plus dietery intake. If she drops below this, she suffers as you do- fatigue etc. Google will tell you that these levels of iron intake can cause organ damage, but that is what she is on, and everything is ok then- bit of a keep fit fan! Keep an eye on the colour of your nails- just look at them with your hand unclenched- they should be pinkish if all ok, whiteish if not as a simple guide. Your doctor is the one to sort this- people on here like me can only suggest, so please try again to get him to help. Good luck