A difficult situation, birdie - balancing the risks of a rectal bleed ( presumably coming from diverticular disease) and the risk of a stroke is not easy. It would be important to keep careful control of the INR ( blood tests for warfarin) so the blood does not get too thin.
Two things - firstly you say the warfarin does not agree with your stomach. What symptoms do you have?
Secondly the low iron reading of 9 - I presume you mean this to be haemoglobin level. Iron levels/stores are measured by the serum ferritin levels.
If indeed you are proven to be iron deficient by blood tests and ferritin level, it may be worth discussing with your GP how this could be improved, asking the advice of the local haematologist if necessary. The amount of iron you are taking is about 12.5mg/day which is not a great deal. You would feel a lot better if your haemoglobin could be raised, as well as providing some kind of reserve against any future bleed.