Brother,
Remember your faith must be in the promise God has given you. John 5:24 says if you hear and believe, you will not be under condemnation. Repent is a change of mind, so at the age of 8, when you heard the gospel, you made a decision to trust Gods promise. You had the freedom to not believe, but you believed. Thank the Lord that you did not go into many sins that others have. Undoubtedly, you were a sinner, because the Bible says all have sinned. If you hadn't sinned, you would not have needed a Savior. And if you have grown as a Christian, that is further evidence, because by your fruits it shows Christ is in you.
He that believeth on the Son hath everlasting life......