UnChristian beliefs often have the pitfall of producing unChristian attitudes. Works based gospels, such as the "gospel" of the Catholic Church, are excellent examples of this. What you believe about how you get to Heaven is guaranteed to affect how you see your chances of doing so, and may even alter your behaviour.
The correct attitude is to see salvation as something that is earned for us, by the Lord Jesus Christ. It is a gift that we accept through faith. We did not, and indeed could not earn it by works. If we got what we deserved, a grand total of 0 people would make it to Heaven. We would all be in Hell. However, in His love, God sent Jesus to die on the cross, enabling all who believe in Him to be saved. Thus, because salvation is 100% from Jesus, our attitude towards salvation depends on exactly how much we trust Him. If we trust Him, we know we're saved, not out of some sense of pride, but because we know who He is. We try our best to respond in gratitude, but when we fail, we don't panic, because it's not on us.
Not so in the Catholic Church, which sets up a series of additional requirements that aren't even consistently applied. Grace, or what they erroneously call grace (Romans 11:6 defines grace and works as mutually exclusive), is handed out piecemeal via the 7 sacraments. It is a works based system. In other words, rather than depending entirely on Jesus, Catholics depend, at least in part, on themselves. This produces one of two attitudes: "I'm so bad, not even Jesus can save me", and "I'm so good, He hardly needs to".
At this point, it's worth noting what I will otherwise be skipping over: The Catholic Church officially teaches that faith is not even necessary for salvation. Aside from Pope Francis telling a little boy that God is proud of his atheistic father who died, the Catechism of the Catholic Church says the following: "Those who, through no fault of their own, do not know the Gospel of Christ or his Church, but who nevertheless seek God with a sincere heart, and, moved by grace, try in their actions to do his will as they know it through the dictates of their conscience - those too may achieve eternal salvation."
Now, as I said, I'm going to be skipping over that train wreck for the rest of this article. Suffice to say, the Catholic "gospel" is almost entirely works based. Because of this, the two attitudes I previously mentioned are all that is really available.
If salvation is based on works, so is our confidence in it. If you are humble enough to recognise the extent of your sin, you are never going to be confident in your salvation. Why? For the same reason you're not going to be confident in a bungee chord you made from your shoelaces! You're never going to be good enough to earn Heaven, and you know it! So why would God let you in? You keep messing up, you keep failing, sometimes you don't even care what's right or wrong. Your confidence in your salvation will be justifiably weak, because you are basing it on your weak self, rather than the immovable rock that is the Lord Jesus Christ.
Yet, ironically, there is more hope for you in that situation than if you have the pride of a Pharisee. Some people bury themselves in their religion. I even remember hearing of one priest who, upon being asked by a Christian if he thought she was going to Heaven, replied "well, I'm a speedboat, and you're a canoe". It is a pleasant thought that you're a good person. Many people don't even need a religion to maintain it. But it certainly helps. If you believe there's a God out there determining who gets to Heaven and who doesn't, and if you can convince yourself that He's quite fond of you because of your dedication to your religion, you get a huge boost of undeserved confidence. There is literally an entire Biblical parable denouncing this attitude (Luke 18:9-14), yet it persists in the modern world.
Ultimately, there is only one way to Heaven: Confess with your mouth the Lord Jesus, and believe in your heart God raised Him from the dead. If you do that, you can have complete confidence that you are saved, and you need to add nothing to that. You don't need to worry that maybe you're too big of a sinner for the perfect Saviour. You're not strong enough for that! And woe betide you if you have the cheek to think He needs your help to save you, because your salvation was never about you. You don't need to earn it; it was earned for you. Therefore repent, and put your hope entirely in Jesus.