Part of what you say is correct; God does know all about us, and nothing we do will ever be overlooked. The Bible warns, "Nothing in all creation is hidden from God's sight. Everything is uncovered and laid bare before the eyes of him to whom we must give account" (Hebrews 4:13).
But this isn't the whole story–not at all! Yes, we have sinned, and our sins are not hidden from God. Furthermore, our sins are serious–so serious that they will keep us out of heaven. The Bible warns, "For the wages of sin is death" (Romans 6:23). You are right to be concerned about your sins, because they will separate you from God, both now and in eternity.
But listen: God still loves you! He loves you so much that He wants you to spend eternity with Him in heaven. And that is why Jesus Christ came into the world. He came for one reason: to take away our sins. He did this by taking upon Himself the punishment you and I deserve through His death on the cross.
Now God offers you His salvation as a free gift–free, because Jesus Christ has already paid the price for it. By a simple prayer of faith ask Christ to come into your life today–and He will. The Bible's promise is for you: "As far as the east is from the west, so far has he removed our transgressions from us" (Psalm 103:12).