When I first considered becoming a Christian I had a number of mental hurdles that needed clearing. Perhaps none bigger than "I need to clean myself up before I can commit to follow Jesus". I now recognize that all humans are incapable of cleaning ourselves. We're splashing in a mud bath, while God stands there with a hose waiting for us to ask Him to wash us up. In Ezekiel God says I will sprinkle clean water on you, and you will be clean; I will cleanse you from all your filthiness.
When one becomes a Christian they grasp that. God is your father who is the only one capable of cleaning you. The problem a lot of Christians have, myself included, is we don't feel clean. Perhaps we have the ability to look back on our former selves and see that we are a lot "cleaner", but clean isn't the term you would use to describe yourself currently. You curse, you're short tempered, you lust after both people and material things. That may be over the course of a single hour! LOL! How can I be clean? We remind ourselves that we were baptized and this is supposed to be my new born-again life! Sin has no power over the born again me!
As always the Bible holds the answers. Paul says in Romans; I don’t really understand myself, for I want to do what is right, but I don’t do it. Instead, I do what I hate. But if I know that what I am doing is wrong, this shows that I agree that the law is good. So I am not the one doing wrong; it is sin living in me that does it. As a reminder this is coming from a man who met Jesus in a miraculous way on the road to Damascus, and then had miracles occur almost every day for the rest of his life as God directed him in spreading the gospel to the world. And yet here he is, decades into his ministry, struggling with sin.
One of the most popular Christian authors of all time is CS Lewis. A man who was such a great Christian that the BBC asked him to speak to his country every night about God! These 15 minute talks began 8/6/41 and continued till the end of WWII. You can hear one of them here, and read more of how he end up on the BBC here. Those talks were compiled into one of the best selling Christian books of all time "Mere Christianity". A synopsis of why Lewis was asked to speak to England was there was a feeling in the church that God was missing from the nation and someone had to wake the people up to the power of prayer and help lead them back to God. That man would be CS Lewis! And yet CS Lewis struggled with perverted S&M fantasies, and alcoholism, often losing those battles. He even famously lost a nationally broadcast debate on Christianity in spectacular fashion, when his thought process was proven to be inconsistent. All of this, and many other struggles, led Lewis to feel like a failure as his biographer notes.
I can list many other great Christian leaders who have had serious doubts about their usefulness to God because of their continued shortcomings including Saint Augustine of Hippo, Charles Spurgeon, and even the great reformer Martin Luther who wrote to a friend as his life was wrapping up about how those struggles served him; "If I live longer I would like to write a book about Anfechtungen [dark nights], for without them no person is able to know Holy Scripture, nor faith, the fear and love of God; indeed he is not able to know what the Spirit is, having never been in temptations".
I believe what Martin was referring to is similar to what Paul was bringing attention to. Doubt is a good thing, because it reminds you that you are weak and need a savior! One of my favorite scriptures is from Ephesians. It's really just part of a sentence. "lest anyone should boast". Of course we aren't to pick just parts of the Bible we like and discard the rest. But that phrase, lest anyone should boast en-captures for me so much of the meaning of God's message. He has to do it all! He wants to do it all! If we could contribute in any way then we could boast of our contribution. We would become prideful. Being a proud Christian should not be possible. In Jeremiah God declares that the only thing a human can ever boast of is knowing God! Or to quote from Animal House "You're all worthless and weak" without Jesus.
God will work on transforming you for the rest of your life. As Philippians says; He who began a good work in you will bring it to completion at the day of Jesus Christ. And while it's absolutely true that by accepting the gift of salvation from Jesus Christ we break the chains of slavery that sin has held on us, we still are not made perfect. I don't pretend to understand why God allows us to struggle for the rest of our lives. I have theories as to why, including it builds character in us, trust in our creator, and keeps us humble. However like a lot of things concerning God He only made us in His likeness, not His equal. So some things I never expect to understand. But God assures us that no mater how grievous our sin, once He begins working on us He never gives up.
In the book of Acts God says He removed King Saul and made David the King. I have found David son of Jesse, a man after my own heart. He will do everything I want him to do, That's quite the endorsement! But by doing everything God wanted, it didn't mean he wasn't going to do things God hated as well. David was 30 years old at the time of his crowning as we know from the book of Samuel. David knew God had been with him since he was very young as he was only 15 when he killed Goliath. He then spent 7 years in King Sauls palace having already been told by the High Priest that he was in fact going to replace Saul. He then fled for 8 years, with God guiding him, in order to hide from Saul who was trying to murder him. After becoming King, to say David backslid is an understatement. David started an affair, impregnated the woman, and ordered the execution of her husband to hide his sin. Yet God stood by him. Restored him. And used him for many great things. God even used that adulteress affair with Bathsheba and made them the great great (25x) grandparents to Jesus Christ! (see Matthew 1-17)
So yes, you're a normal Christian if you struggle with your sinful nature. More importantly the fact that you're struggling serves as proof to you that the Holy Spirit is alive in you and is working to change you. And finally God can use you and your faults long before you're ever "perfect" as none of us will be perfect till Jesus returns.