One of the Bible's greatest truths is that when we turn in faith to Christ, God forgives us and accepts us just as we are.
In other words, we don't have to become perfect before He'll accept us, nor do we have to get rid of all our faults before He'll welcome us into His family. The Bible says, "But God demonstrates his own love for us in this: While we were still sinners, Christ died for us" (Romans 5:8). God knows what we are like, and He loves us just as we are. Thank Him for this truth!
But once we come to Christ, God has a plan for us—and His plan is that we would become more like Christ. In other words, God doesn't want us to remain spiritual infants (which is what we are when we first come to Christ). God wants us to become spiritually mature and strong in our faith. The Bible says, "Like newborn babies, crave pure spiritual milk, so that by it you may grow up in your salvation" (1 Peter 2:2).
How does this happen? One of the ways God has given us to grow spiritually is through fellowship with other believers. And that's why I hope you can find ways to overcome your shyness, and little-by-little become connected with other Christians. The Christmas season would be a good time to do this, incidentally; many churches have special programs that attract visitors, and you can attend them without feeling embarrassed.