Knowledge of your sin For if we go on sinning willfully after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, but a terrifying expectation of judgment and the fury of a fire which will consume the adversaries


~ Hebrew 10:26-27

Just what is knowledge of your sin? Is it being told / someone agreeing with you? Only when the bible says is sin? What if you feel uneasy about what your doing? If feeling uneasy and know your doing wrong is a sin, what about doing something to protect those you love (fighting, not out of rage) or displaying tough love. Or rather, how does the bible separate knowledge of sin, the feeling you've done something wrong, and actual sin?
I'm going to try my best, but please correct me if I stated anything incorrectly. It seems that most of your question lies in the separation between:


  1) knowledge of sin
  
  2) feeling of sin
  
  3) actual sin


In relation to "the knowledge of the truth". 

Well first off, what is "knowledge of sin"? Where do we get that? Romans 3:20 says:


  Therefore no one will be declared righteous in God’s sight by the works of the law; rather, through the law we become conscious of our sin.


With this, we can figure out that God's law is how we become conscious of our sin. This is how we are able to find out we are sinners. If I am correct, this is referred to as "revelation". Knowledge of our sin is revealed to us through God's Word and His standards (the law). 

Further we have Romans 7:7:


  What shall we say, then? Is the law sinful? Certainly not! Nevertheless, I would not have known what sin was had it not been for the law. For I would not have known what coveting really was if the law had not said, “You shall not covet.”


What about "feeling of sin" and "uneasiness of sin"? I am unsure about how to answer you for this. Feelings are quite subjective and are hard to use as a basis. However, there is "conviction of sin" which goes a little deeper. This is because feelings are strongly tied to emotions whereas conviction involves a change of attitude toward sin. This is displayed by Joseph in Genesis 39:9 and Isaiah in Isaiah 6:5. They had a change in attitude toward sin. Note that this is different than having simply shame or a guilty conscious that anyone may have without any change in their action. "Uneasiness of sin" may be "conviction of sin" and since "knowledge of sin" is revealed through God's law, that should be the place to go to find out if that conviction is real.

Actual sin is any act contrary to the will and law of God. This can be through omission or commission. If you are truly concerned with whether something is an actual sin or not, sometimes it's best to check whether it is "definitely good" or "glorifying to God".

For this, there is Romans 14:23:


  “Everything that does not come from faith is sin”


And 1 Corinthians 6:12:


  “Everything is permissible for me—but not everything is beneficial. Everything is permissible for me—but I will not be mastered by anything”


There are some other passages you can check such as 1 Corinthians 10:31. Hopefully this would help clarify what is "not sin" so that you can know what "is sin".