What should I do about my constant feeling of impurity, my continuous thoughts about the uncleanness of everything I touch, and my inability to distinguish between types of discharge?

This doubt is from the whispers (waswas) that one is advised to ignore. As for the discharge, it is from the pure vaginal fluids, but it invalidates ablution (wudu'). If you doubt whether what came out is maniyy (seminal fluid) or something else, many scholars hold that you have the option to choose between what you doubted and assign it the ruling of one of them. We advise you to avoid watching what displeases Allah Almighty.