help! nursing while pregnant

I just found out that I am pregnant, and I have an almost 8 month old son. He only drinks breastmilk (no formula) and now I am so scared my milk supply will decrease or dry up now that I am pregnant. I really want to breastfeed to 1yr so I am looking for any tips on how to safely increase your milk supply while pregnant, or success stories of mommas who have breastfed a baby while pregnant without having to switch to formula.