I am currently tandem feeding my 21 month old son and my 9 month old daughter. On this website I was given a link which I found comforting:

http://www.breastfeedingbasics.com/html/nursing_during_pregnancy_and_tan.shtml

During very early pregnancy I experienced some nipple tenderness and felt like my milk production was decreasing but I made sure to drink plenty of water until the feeding seemed normal.

I was approached by a woman who said she was a lactation consultant and she expressed her pleasure in meeting someone who persevered in feeding two.

I love the convenience and bonding and also the understanding my two babies have when it comes to sharing. If I became pregnant again I still wouldn't rush my son into weaning! (Even at the risk of becoming a circus attraction)

I should warn you that 90+% of people you meet will think it strange but those around you get used to it and even admire it.

The other problem I had was in the first days after the birth my husband didn't visit until mid afternoon by which time I was desperate for my son to relieve me from engorgement in each breast !

Hello, here is a link to Tanya's great advice/article that she wrote in regard to her current experiences with breastfeeding during her pregnancy - you might find it helpful.

http://www.minti.com/parenting-advice/6463/Breastfeeding-through-pregnancy/

i have been told that its good for baby as the milk is already there and you are already producing all the nutrients baby will need, and you dont have to worry about when your milk will come in it already there

There are a few great books sold about tandem feeding. One is called Adventures in Tandem feeding.
While pregnant my understanding is your ilk reverts back to colostrum. Some children wean when you become pregnant some don't like the taste others love BF even more.
Perhaps contact a breastfeeding counsellor and discuss your options. They can give you all the information you need. They have several booklets and books sold through mothers direct as well.