i wouldn't let someone's suggestion scare you. I think that is bad practice/medicine. Alot of the things you named are normal - talking to yourself, being somewhat paranoid (especially when you are depressed).

My brother who was initially diagnosed with schitzophrenia had a three week long delusion. It wasn't gradual for him. It was debilitating. I'm not sying that it is like that for everyone. But really..why worry yourself when you don't yet have the symptoms and if you are older you most likely won't develop it as it usually shows itself in the early to mid 20s. I'm not sure if I helped at all. But I think of this one wisdom which says basically says .. What good does worry do? Can it add one day to your life? Instead trust.

Easier said than done.. yup.. but I truely believe this situation applies because you seem to be going through depression and encountering some of the negativity that comes with that.