I think the reason why he is querying the aneamic thing is that the baby relies on its birth born store of iron and that generally runs out by about 6 months. There are lots of pieces of research that does show if a mother exclusively bfeeds her child after 6 months, there can be risk of iron deficiency. However, as far as I am aware it only applies to exclusive bfeeding, and if your child is eating other foods then it should not be a problem. But that may be why he wants you to encourage a full diet as well as bfeeding. I can send you the research if you want it, but probably not!
However, having said that, Cows Milk is even less in iron, but I guess his thinking is that Cows Milk is more of a drink, whereas BMilk can be subsituted for a meal.
However, on the other things, I think he is talking out of his arse. You do need to get a balance between bfeeding and food as at this age, I don't think bmilk does give all the nutrients a child needs (such as iron) and they can get them more effectively from other foods. But if your other foods are high in iron, for example, then there shouldn't be a problem!
I also believe that there are medical benefits from bfeeding past a year, and it is mainly immunity based - (But can't rememember what exactly off the top of my head). But if you want to arm yourself with some facts... Try looking up www.bmj.com and follow the links to searching other journals. You should then be able to find abstracts from articles about bfeeding from the Amercian Academy of Paediatrics. It won't give you the whole document, but you can get a flavour of the articles and the views.
Then next time you see your GP and he mentions it, take a very deep breath, smile sweetly and (think patronising) say that as a doctor, he probably knows more up to date research than you, but you had been told by a friend that bfeeding past a year was recommended by American Association of Paediatrics... and you had believed that XXX article had recommended it. And did he know of any research which had proved this false, etc?
I find it works excellently every time... Boost their ego with a compliment about their status, and then very politely prove you know far more than they do. Shuts them up every time!!
Hope This helps
And keep going - I still Bfeed my 16 month baby and my HV is completely behind me. I don't think she'd dare not be!!!