Hi J.,
Both of my kids were formula fed - both are healthy, happy and smart. Please try not to worry. (I know, easier said than done).
Both of my kids drank soy formula. We used Similac soy with my daughter, the first child. Our son drank Similac soy for a while, but then we switched to Member's Mark soy, the Sam's Club brand and every so often used Target brand too.
I did find that the soy formula seems to stain things yellow. Even bleach didn't help. Use lots of bibs and burp rags. I suggest non-white.
By the way, when it came time for regular milk, my daughter did just fine, my son did not - he was, and continues to be lactose intolerant - a family trait. He drinks Lactaid brand milk. Oddly, he doesn't like soy milk.
Good luck!
P.S. I don't think there was organic soy formula when my kids needed it so I don't have any advice about that.