Not only is it possible that God did not reveal to us absolutely everything that He did in the Bible, but I know He didn't.
But that doesn't prove that He did. I can only rely on what He said He did. Not on what He might have done and it looks like the latest science (i.e. this article) seems to support the Bible's perspective that there is only one earth...
But my point was that we really can't claim knowledge of whether or not life exists on other planets, either from a religious or a scientific perspective. I think you've just confirmed that point, at least from the religious perspective. God has given us no reason to believe that there are other planets with life. On the other hand, He has not specifically told us that these other life-bearing planets don't exist.