In my Christian life I believed that God wanted me to be with Him in heaven. But that is not what the Bible says.
For whom He foreknew, He also predestined to be conformed to the image of His Son, that He might be the firstborn among many brethren. Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified.~ Romans 8:29-30
You therefore must be perfect, as your heavenly Father is perfect. ~ Matthew 5:48
The idea is you must not have any sin to get to heaven. We must be perfect. This is the reason Jesus died, so we could be sinless in heaven.
But the sinless me is not the real me. I have flaws and do good things and bad things. God does not want to be with me until I am perfect and without sin, only doing good like His son. God wants me to be like Jesus to be with me. God wants Jesus clones, He loves Jesus not me.
I think you are on the right track. You ask the right questions.
Yes, He expects us to be perfect but also remember that He makes you perfect.
The problem is sin. Paul says in Ephesians 2 that we were, by nature, children of wrath; we were born dead in trespasses.
So, why did Jesus have to come? For sins. His work had to do with sin. What He, as God, had to do was to deal with sin.
How?
What is the solution? - there is forgiveness with God. Forgiveness is the answer to the problem of sin and He has provided it in Jesus Christ. Look again at MT 26:28 “For this is My blood of the covenant which is poured out for many for the forgiveness of sins.”
Your issue might be here - do we deserve it? Do we have to be good enough to warrant it? NO!
We can count on that forgiveness because that forgiveness of God is not based on us deserving it, or on us repenting hard enough or often enough - but it's based upon the atoning death of Jesus Christ.
God forgives us not because of us, but because of His Son. That's why Jesus’ forgiveness if forever.
"This is my blood of the covenant, which is poured out for many for the forgiveness of sins."
God forgives you not because of your faith, not because of your repentance, not because of something good you have done; God forgives you because of Jesus Christ.
How do you receive this forgiveness?
By faith.
You get that forgiveness by faith. You are accepted and forgiven by God by trusting/believing in a righteous substitute - Christ.