If your salvation is the real thing: no, you cannot lose it. Why? Because the real thing comes from God and God is perfect.
If your salvation was walking down an aisle, saying one prayer, making a pledge: these are man’s ideas of salvation, not God’s, then YES you can lose it because you never had it.
You mentioned that you see sin in your life. I know how the weight of past sins can be tremendous. But that is exactly why the Bible says “Repent and believe”. We must truly repent, which means to feel the full weight of our sin and find disgust in our sin. Then to go to God whom we have sinned again in every sin we commit and ask His forgiveness and repent.
If this is happening to you, ask God to help you overcome each sin as it shows up in your life. I have had to pray VERY HARD for some sins to be removed (and God has Graciously answered my prayers) and others only once.
Mostly the majority of sins I used to commit without them even bothering me in the slightest, have become things I can NO LONGER DO. Not because of rules. Or trying to look good in Church. The Holy Spirit in me hates them so much I can’t imagine doing them now.
Knowing that you are sinning is one thing. Knowing that you are sinning and being VERY troubled by it, especially if it leads to fears of losing salvation is more like an alarm for you, a wake up call. God is telling you those things are not acceptable to Him. Repent of them and ask His help to overcome them.
John 10:27-31 New International Version (NIV)
27 My sheep listen to my voice; I know them, and they follow me. 28 I give them eternal life, and they shall never perish; no one will snatch them out of my hand. 29 My Father, who has given them to me, is greater than all; no one can snatch them out of my Father’s hand. 30 I and the Father are one.”