Do you struggle with assurance of your salvation? One thing is certain, if you have never had to deal with the possibility that you are eternally doomed then you have missed something essential. Even if it was in a very brief moment when you saw the value of Christ's cross and trusted immediately.
Some agonise over whether they are saved for years rather than for moments, but in this agonising is the work of the Spirit.
Remember that a bruised reed he will not break, a smouldering wick he will not put out (Isaiah 42:3). Also remember that whoever comes to him he will never cast out (John 6:37). But you have to work out the balance between these verses and whether you are one who has said Lord, Lord (yet he will say he never knew you (Matthew 7:21)). The Spirit, and your assurance, is in and through this battle.
A tale of assurance worth reading: