Is the questioner considered to have denied other matters that he should have denounced to his non-Muslim teacher, but did not?

It appears from the question that the questioner is afflicted with waswasah (obsessive whispering), and the effective cure for this is to disregard these whisperings. In the Arabic language, juhood (denial) means to disavow something. In Islamic law, it refers to concealing the truth while knowing its veracity, and it is a type of disbelief, like the disbelief of Pharaoh. What the questioner did is not juhood; rather, it is a failure to verbally denounce an evil that he was capable of denouncing. He must denounce evil with wisdom and good admonition.