You just demonstrated that you misunderstand. It's not about must confess "this" list of sins, but don't have to confess "that" list of sins. Rather than focusing on confession of every single sin that we commit as we commit them as an additional requirement to remain cleansed (continuous revolving door of sin - uncleansed/lost again; confess - cleansed/saved all over again) and if we forget a sin we are toast, John has in mind a settled recognition and ongoing acknowledgment that one is a sinner in need of cleansing and forgiveness. While false teachers/unbelievers say they have no sin "present tense" (vs. 8) or say they have not sinned "past tense" (vs. 10) Christians confess their sins. The term "confess" means to say the same thing about sin as God does, acknowledge His perspective about sin, which is on an ongoing basis.
The Greek word for "repent" is "metanoia" (noun) and "matanoeo" (verb) you see as defined in the Strongs #3340, 3341: to think differently or afterwards, reconsider. After thought, change of mind. This change of mind is on an ongoing basis. So repentance basically means a "change of mind" and the context must determine what is involved in this change of mind. Where salvation is in view, repentance actually precedes saving faith in Christ and is not a totally separate act from faith. It is actually the same coin with two sides. Repentance is on one side, what you change your mind about and faith in Christ is on the positive side, the new direction of this change of mind. *Repentance and faith are two sides of the same experience of receiving Christ.
The Bible also tells us that true repentance will result in a change of actions. Acts 26:20 declares, "I preached that they should repent and turn to God and prove their repentance by their deeds." This is the fruit of repentance (Matthew 3:8), not the essence of repentance (change of mind). Works-salvationists confuse the "fruit of repentance" with the "essence of repentance" (and also do the same thing with faith) and end up teaching salvation by works.
I have heard certain people say, "If you want to be saved, repent of your sins, turn from your sins." If turning from your sins means to stop sinning, then people can only be saved if they stop sinning. And in that case, it is unlikely that anyone will be saved, since we don't know anyone who has ever "completely stopped sinning" yet there are some deceived individuals who teach "sinless perfection" and believe they live a sinless, without fault or defect, flawless, absolute perfect life 100% of the time (exactly as Jesus lived) and are suffering from a terminal case of self righteousness (1 John 1:8-10).
Those who have repented/those who are born of God no longer practice sin (1 John 3:9; 1 Corinthians 6:9-11; Galatians 5:19-21); but instead, practice righteousness (1 John 3:10). The idea of practice is to perform repeatedly or habitually and thus describes repetition or continuous action. This describes the practice of sin in 1 John 3:9 as habitual, as one's lifestyle or bent of life without goal or effort to stop, no repentance, just bring it on.