I am schizoaffective, bipolar version, so I get delusions and hallucinations.

I went to my psychologist for my bi-monthly appointment, and we talked for a while and then I did my usual interogation at the end. We talked about how I checked doors and locks late at night, and he says it's OCD. Never told me that before.

What I am confused about, is that I always figured it was related to my fear that people are going to a) burn the house down b) come into my house and murder me or c) try to watch me. I just figured it was some kind of delusion... but apparently it's OCD?

Are the lines blurred between these two things? I am just confused. Do I go on medication now? What exactly happens after being diagnosed with OCD?