How do i know that i am 100% going to make it to Heaven?

As Christians, we are still sinners, even though we are in a close personal relationship with Jesus, and we sometimes do things that we really don’t want to do. But God knows that we are sinners, and doesn’t love us less when we sin. All He wants is for us to come to Him, ask for forgiveness, and keep walking with Him. He wants to help you, so just keep on coming back to Him, no matter what. The apostle Paul was on of the greatest Christians in the Bible, but he also had a problem like yours. Look at what he says.

Romans 7     ¹⁸ For I know that good itself does not dwell in me, that is, in my sinful nature.  For I have the desire to do what is good, but I cannot carry it out. ¹⁹ For I do not do the good I want to do, but the evil I do not want to do—this I keep on doing. ²⁰ Now if I do what I do not want to do, it is no longer I who do it, but it is sin living in me that does it.

2 Peter 3:9   The Lord is … not willing that any should perish but that all should come to repentance.

1 Timothy 2     ³ For this is good and acceptable in the sight of God our Savior, ⁴ who desires all men to be saved and to come to the knowledge of the truth.

So if Paul had a problem of doing things that he did not want to, then you should not think that you cannot go to heaven. Just keep on asking God to transform your character, change your heart, and He will help you to become what He wants you to be. Meanwhile, if the devil gets to you, and you find yourself doing things that you really don’t want to, just go to God immediately, and He is keen to help.

I hope that this makes sense to you. God bless!