How do you know when you are truly saved, and how do you live as a Christian afterwards? I'm 18 years old, and I was born in a Christian family (Evangelical), so I've been going to church and believed in Jesus my whole life. However, I am concerned about salvation. According to what I know, to get saved you have to repent, believe in Jesus, and try to sin as little as possible afterwards. However, I think there are more requirements because I do all of those things but I'm not really sure if I'm saved. Whenever I do sin I repent again (I pray for forgiveness) I know that many people would even consider me unsaved since I asked this question, because supposedly when you are saved you know it for sure and are confident. But the reason that I included my background in the question is because I am already saved, but I just don't see a difference because I don't have the luxury that a non-believer-turned-Christian would have. That is, I can't compare my current situation with my very sinful past and see a distinction, because I've always believed in God. What do you think? I think that even if I am saved, my lack of confidence shows that I am very weak. (By the way please be as direct as you need, and do not worry about offending me at all; this is a very serious topic and I need to know the answer).

P.S. Please include any relevant passages for me if you have any in mind.
Of course the answer will depend on which Christian tradition the answerer comes from, but since you requested passages from Scripture on the matter, here are a few to consider:
Is Jesus your Lord?

if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved -Romans 10:9

Do you live for Jesus?

He died for all, so that they who live might no longer live for themselves, but for Him who died and rose again on their behalf. -2 Corinthians 5:15

Do you lay down your own will to follow Jesus?

If anyone wishes to come after Me, he must deny himself, and take up his cross daily and follow Me. -Luke 9:23

Are you led by His Spirit?

all who are being led by the Spirit of God, these are sons of God. -Romans 8:14
In Him, you also, after listening to the message of truth, the gospel of your salvation—having also believed, you were sealed in Him with the Holy Spirit of promise, who is given as a pledge of our inheritance, with a view to the redemption of God’s own possession, to the praise of His glory. -Ephesians 1:13-14