How do I start becoming more involved in church?

Move gently into the environment you seek. If the message (the meat of the service) is not reaching you, convicting you in your heart, perhaps you are attending the wrong service. There is no need to walk in the door and proclaim all your sins. Your sins are between you and the Lord. Confess it to Him and ask His forgiveness. It will be given unto you. When, in time, you cannot forgive yourself or stop focusing on what you've done, ask for His help. He will give it. Once you are a member of a body of His bride (the church), I pray that you cannot be cast out. Only the One True God can cast you out. Let them judge you not, lest they be judged.