What must I do after I swore to stop masturbating, then said "Insha'Allah" a period of time later that I don't recall, then returned to it out of ignorance of the ruling? And is this question of mine considered publicizing a sin?

The person who swore an oath, then made an exception, but whose "in shaa' Allah" (God willing) was not connected to their oath, must repent and offer an expiation for a broken oath (kaffarat yamin). This is because the lack of connection in the exception invalidates its effect. Doubt about the connection of the exception is not taken into account, as the default is the validity of the oath and the obligation of expiation upon breaking it, and certainty is not removed by doubt. Your question is not considered an open declaration of sin, because it serves a legitimate Sharia purpose.