Is the questioner considered an unbeliever for performing prayers while believing that the discharges that exit a woman do not nullify ablution, or for her negligence in researching its ruling? And must she make up the prayers of 8 years or only the prayers of two weeks?

You are still upon Islam, but beware of giving in to the whispers (waswas) concerning faith, prayer, and purity. Vaginal discharge (rutubat al-farj) is pure according to the preponderant opinion, but it nullifies ablution (wudu') according to the majority of scholars. There is no contradiction between its purity and its nullifying of ablution, just like wind. You are required to perform ablution because of this discharge. If you are afflicted with its frequent emission ( سلس - سلس البول والغائط والريح ونحوها), then perform ablution for each prayer after its time has begun. As for past prayers, you are not required to make them up, due to your ignorance of the ruling and due to the concession granted to those afflicted with waswas.