I will tell you what I see though, if you want.
I do not think Paul was saying that until he heard the law, sin was not in him. I think he thought the sin was in him but he would not have KNOWN it was sin, except that the law told him it was. Otherwise, to my mind, we are saying that he was sinless until he heard the law, and then the law made him a sinner, which he seems to strongly want to convey is NOT the case when he says: well then, am I suggesting that the law of God is sinful? Of course not! In fact, it was the law that showed me my sin!
He is saying (to my understanding) that the law showed him what a sinner he was, not that the sins he committed were not sins before that.
I think a sinner is a sinner whether he knows he's a sinner or not.