The most important thing I can tell you is that when you turned to Jesus Christ and gave your life to Him, you became His child forever. Nothing will ever change that relationship - nothing. The Bible says, "How great is the love the Father has lavished on us, that we should be called children of God! And that is what we are!" (1 John 3:1).
You see, when Jesus Christ died on the cross, all your sins were placed on Him. He was without sin, for He was the perfect Son of God. But on the cross He willingly took upon Himself your sins and mine, and He endured the judgment that you and I deserve. When we trust Him as our Lord and Savior, God forgives our sins - fully and freely - and adopts us into His family forever. If you sincerely gave your life to Christ, this has happened to you. Even if you sin, you still are God's child.
Why, then, do you still struggle with sin? The reason is because your old sinful nature still lives within you. It tries to rule your life and make you live like you did before you committed your life to Christ. But God also lives within you by His Spirit, and He wants to help you overcome your sins.
When you sin, ask God's forgiveness right away. Then ask Him to help you take steps to avoid it in the future. Most of all, learn to walk with Christ every day, committing every situation to Him in prayer and walking in obedience to His Word, the Bible.