Megan - I personally wouldn't bother with cow's milk. While the WHO ideal is 2 years, nutritionally breastmilk is most important for babies in the first 12 months. So as long as he is eating well, has a healthy, balanced diet including dairy and having some breastmilk I think he'll be just fine.

You could always speak to your GP or paed (if they are 'breastfeeding friendly') or give the ABA helpline a call if you are unsure.