How can one overcome the contradiction between adhering to the Salafi methodology and offering advice to others, on the one hand, and relapsing into the temptations of desires and sins committed in private, which have led to obsessive-compulsive disorder and shortcomings in acts of worship, despite attempts at psychological treatment and maintaining some rituals?

You must lower your gaze from women and avoid all provocations. Be careful not to approach them or anything that might lead to temptation by them. Marry a righteous woman who will help you remain steadfast and continue your da'wah efforts. The cure for inner conflict is to continue doing good deeds and associate with good people. As for obsessive thoughts (waswas), the cure is to ignore them and occupy your time with what is beneficial. Be wary of being alone, and there is no harm in seeking ruqyah (definition) (Islamic exorcism) and consulting psychiatrists.