CONGRATULATIONS! I hope that it is a blessing for you - what a shock, though. I'm sure other moms can chime in about bf while pregnant. You might even want to start another thread. I'm sure your lo was fussy because of that. I've heard that the milk can even change it's taste.
Anyway, in my experience, my supply dropped quite a bit when I got pregnant. We made it nursing about one month after I got pregnant and then when my baby started waking up at night again to feed and I kept getting sick, I put him on goat's milk. I continued to nurse him first thing in the morning and before he went to bed at night until he was 1 year old. But I don't think he was getting anything. Anyway, the drop in supply was just my experience. I know some moms can successfully bf throughout their whole pregnancy. Let us know how it goes for you!
And congratulations again.