Can you be schizophrenic with hardly any positive symptoms?

Yes, but not often. The "residual type" of schizophrenia is characterized by an absence of prominent positive symptoms (e.g., delusions, hallucinations, severe behavioral disorganzation). To be diagnosed your doctor would assess for other symptoms and for major problems in social/occupational functioning. In addition, these serious problems must have been present for quite a long period of time (at least 6 months).