Thank you for your long answer. It sounds like you had a well-formed conscience in spite of the fact that you had so many influences around you to misguide it!
So yes, as you were told by therapists, your conscience “should” have been badly formed, but you by the grace of God beat the odds and were able to connect with a deeper part of yourself. Congratulations! You are not saying that other people can not have a malformed conscience, though, as the CCC says conscience formation is a life-long process:
“Knowing what we are doing when we sin”, though, is more than just the conscience. First of all, “knowing what we do” means that we are not blinded by desire or resentment, which is very often the state of mind when people sin. The test for this is, does the person regret his action later, such that he would not repeat his sin? If the answer is yes, then there was something he did not know when he sinned. If the answer is no, then his conscience is malformed.
Another part of “knowing” could be called the “love test”. Would the person commit the same sin against his own mother, against his own child? If the answer is no, then the person’s value of human dignity is underdeveloped, he is immature in empathy toward other people. If the answer is yes, then he is blinded by despair.