Are these whisperings considered disbelief —despite trying to ignore them and not believing in them—?

One must not pay attention to intrusive thoughts (waswasa) and strive against the self by completely ignoring them, for that is an act of worship to Allah and an act of disobedience to Satan. Your aversion to these intrusive thoughts is a sign of sincere faith. Allah does not hold a servant accountable for what passes through their mind as long as they do not speak or act upon it, as affirmed by the Prophet, peace and blessings be upon him: "Indeed, Allah has forgiven my Ummah for whatever crosses their minds, as long as they do not act upon it or speak of it." One must ignore obsessive thoughts and not be distressed by them, and continue to do so until they gradually disappear, while making abundant supplications at times when prayers are answered.