Anaemia caused by bf? Anyone else?

No, not heard of this but hope gp has advised you re diet and any supplements you need. Breastmilk doesn't have a lot of iron in it, what it does have is well absorbed though. Most bf babies run low on iron around 6mo so crucially they need iron rich foods around then. I don't know if you being anemic will have affected the iron in your milk? Do seek advice from gp re your babies needs as well, seeking out iron fortified foods for baby and naturally iron rich things for them might be good too. They need a surprising amount given small tums.

I doubt it is due to breastfeeding. Lots and lots of women have borderline/ slightly low iron due to years of menstruatung. You will also have lost some during birth.

In the distant past women would have been pregnant or breastfeeding most of their fertile lives, so having years of regular menstruations is a relatively new phenomenon.

Breast milk doesn't contain much iron (although what it does have is well absorbed by baby so is sufficient) and breastfeeding delays the return of menstruation, so I can't see how that would have a significant impact.