Hi,

Congratulations! As with many things breastfeeding (and concerning babies in general!) there is no clear script! For about 70% of women, their milk supply seems to diminish markedly around the 12 wk period. If you are just pregnant, that should be around when your baby is 12 mnths old. As your baby is taking foods other than breastmilk as well, you should be able to keep feeding and then just put your child onto cows milk from a cup at 12 mnths. If you and your baby desire, you can continue to breastfeed right through the pregnancy and tandem feed both. In some circumstances the baby will seem to lose interest in breastfeeding, and self wean during the pregnancy. For many women this is also a welcome outcome.
I recommend highly Hilary Flowers' book "Adventures in Tandem Feeding"
Regards
Barb