If we are truely sorry and ask forgivness, will God forgive ALL sins asked through Jesus Christ?
Don't worry about it. The forgiveness is already there, it's the repentance that takes advantage...or makes use...of it.
If we could control our sinning, Jesus' sacrifice was for nothing. We, as grateful, reborn (regenerated) Christians have the Holy Spirit which works in us to love the Lord and want to obey him, not because we are required to for salvation but, because we love him and want to not sin. So we struggle with sin...fighting the good fight of faith...our whole lives.
Don't get caught up in "works", focus on faith. It is the Holy Spirit which works in us to do good. If anyone focuses on doing good works, they lose sight of the gift that is by faith because they get caught up in stressing about doing good which can lead to boasting and other faithless things. It is the heart the Lord wants, not sacrifices...or deeds. If God has the heart, he also has the good deeds that go along with the faith in that heart.
Anyone who has the true faith will find it is a much more difficult life than one one who is simply trying to live a good life.
God's assessment of our works will be determined on our faith. If we have faith, we have works. If we don't have faith, no amount of good deeds will help us at the judgment. Here, I'll just let Him speak for himself:
James 2:18 NIV
Show me your faith without deeds, and I will show you my faith by what I do.
You foolish man, do you want evidence that faith without deeds is useless? Was not our ancestor Abraham considered righteous for what he did when he offered his son Isaac on the altar? You see that his faith and his actions were working together, and his faith was made complete by what he did. And the scripture was fulfilled that says, "Abraham believed God, and it was credited to him as righteousness," and he was called God's friend. You see that a person is justified by what he does and not by faith alone. In the same way, was not even Rahab the prostitute considered righteous for what she did when she gave lodging to the spies and sent them off in a different direction? As the body without the spirit is dead, so faith without deeds is dead.
Romans 8:1-11 NIV
Therefore, there is now no condemnation for those who are in Christ Jesus, because through Christ Jesus the law of the Spirit of life set me free from the law of sin and death. For what the law was powerless to do in that it was weakened by the sinful nature, God did by sending his own Son in the likeness of sinful man to be a sin offering. And so he condemned sin in sinful man, in order that the righteous requirements of the law might be fully met in us, who do not live according to the sinful nature but according to the Spirit. Those who live according to the sinful nature have their minds set on what that nature desires; but those who live in accordance with the Spirit have their minds set on what the Spirit desires. The mind of sinful man is death, but the mind controlled by the Spirit is life and peace; the sinful mind is hostile to God. It does not submit to God's law, nor can it do so. Those controlled by the sinful nature cannot please God.
You, however, are controlled not by the sinful nature but by the Spirit, if the Spirit of God lives in you. And if anyone does not have the Spirit of Christ, he does not belong to Christ. But if Christ is in you, your body is dead because of sin, yet your spirit is alive because of righteousness. And if the Spirit of him who raised Jesus from the dead is living in you, he who raised Christ from the dead will also give life to your mortal bodies through his Spirit, who lives in you.
Matthew 7:18 NIV
A good tree cannot bear bad fruit, and a bad tree cannot bear good fruit.
Philippians 3:3 NIV
For it is we who are the circumcision, we who worship by the Spirit of God, who glory in Christ Jesus, and who put no confidence in the flesh...
Philippians 2:13 NIV
...for it is God who works in you to will and to act according to his good purpose.
Ephesians 2:8-10 NIV
For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— not by works, so that no one can boast. For we are God's workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do.