I have not heard of this particular phenomenon with OCD yet. (I have heard of OCD with psychotic features, referring to when the person really believes some of the obsessions, that is, they become something like delusions).
Anyway, I am not sure what to tell you. You have told your doc and he says he has heard of it as part of OCD before, so that's somewher eto begin.

Sometimes there are also symptoms that do not fit an exact category. I think it would be dangerous to just conclude "seeing things - must mean schizophrenia". Oh no, I am sure there are a lot of different causes for seeing things.
A question to ask yourself: When you see these faces, etc, does it evoke similar feelings as your obsessions? Anxiety maybe? Do you obsess over the things you see?
When I first read the title to your poast I thought of something I used to struggle with a lot: "Seeing" things to obsess over everywhere. It got to the point where I could hardly look out the window of a moving vehicle anymore, because I would see things to obsess over so often that I would have to get off at the next bus stop or whatever a lot.
So maybe OCDers have a very finely-tuned visual system? This is just a thought, that there might be a connection here.
Best wishes!
Kathrin