If you sincerely asked Christ to come into your life–even if you were too young to understand everything that it meant–then He heard your prayer and saved you from that moment on. The Bible's promise is clear: "If you confess with your mouth, 'Jesus is Lord,' and believe in your heart that God raised him from the dead, you will be saved" (Romans 10:9).
Do you remember the way Jesus welcomed children who wanted to come to Him? On one occasion, His disciples tried to hold them back. But the Bible says that "When Jesus saw this, he was indignant. He said to them, 'Let the little children come to me, and do not hinder them, for the kingdom of God belongs to such as these" (Mark 10:14). He rewarded them for their childlike faith.
The real question, however, is this: Are you–right now–trusting Jesus Christ and what He did on the cross for you for your salvation? In other words, don't focus just on the past and whether or not you truly gave your life to Jesus then. Focus instead on Christ and what He did for you, and be sure your trust is in Him. If you are uncertain, decisively commit your life to Him now.
Then make it your goal to walk with Christ every day. Just as children should grow into adults, so God wants us to grow and mature in our understanding and faith.