Hi Adele, thanks for sharing your situation. I have RV endo stage 4, polyps & fibroids and have been diagnosed severe anaemia & iron deficient anaemia on and off for 18 months (I needed a blood transfusion for low haemoglobin once, and have regular iron IM injections as an ongoing treatment for the low iron)
As well as the treatments, I've adjusted my diet to help increase the amount of iron in my food. You could maybe explore this as well as taking the medication you've been prescribed? I was also advised to eat vitamin c rich foods to help retain the iron and advised not to have a caffeinated drink for at least half an hour after eating as this can stop iron absorption from anything you've just eaten. I sometimes eat meat 'medicinally' after my period, though Ive only just started to do this and includes frying up some chicken liver, when I remember. The change in diet has been beneficial, particularly noticeable when Im having a period, I'm not as constipated as I had been during my period, and this has also reduced some pain.
My anaemia was initially thought to be linked to the endo, then my endo specialist nurse thought the polyps were more likely to be the cause of the heavy bleeding, so it may be worth investigating that? According to the endo nurse, the possibility of removing the polyps could reduce the amount of blood loss. This isn't an option for me but it maybe worth asking for a scan to rule it out? I was diagnosed with RV endo in 2006 and the polyps possibly causing heavy bleeding was only mentioned last year.
I do notice the difference between the two anaemic deficiencies and recognise when Im not feeling well, since after treatment I have a bench mark of what 'well' should feel like; so now I book myself in for blood tests when I'm feeling depleted. It may be worth having a conversation with your practitioner to establish that you can do that too if it continues.
Hang in there and hope you start to feel the benefits of treatment very soon