"What if my good deeds outweigh my bad deeds?"
Even if they did, that's not how justice works. Imagine today you did a crime in the morning, but then in the afternoon you helped three people out.
When the police ask you about what you did, you say, "Surely me helping those three people out covers the crime, right?" The police would not agree.
Same thing in the sight of God, your good deeds will not cover the bad deeds you've done. And since God's standard is perfection, that is why we need a perfect person to take our punishment for us.
That's what Jesus did on the cross 2000 years ago for those who would believe in Him, providing the way you can be certain you're going to heaven.