It takes a psychiatrist, and usually a second opinion doctor to formally diagnose schizophrenia, after a never of symptoms over a period of at least a year.
The most common positive symptoms are: hallucinations- experiencing stimuli that are not actually present, they are categorised under the acronym VATGO. Visual- seeing things, auditory- hearing things. Tactile- feeling things. Olfactory- smelling things and gustatory- tasting things.
Delusions are: a false, fixed belief that defies rational logic or explanation. A person may be paranoid that others are after them, feel that they are special or gifted.
The negative symptoms of schizophrenia are isolation, a lack of motivation or enthusiasm etc
The way to remember is that positive symptoms are things that add to a person, and that negative symptoms take away- they are harder to treat.
Some meds for depression- venlafaxine for example are also used for schizophrenia, but most anti-psychotics are to reduce the symptoms such as delusions or hallucinations, or the negative symptoms.
Does your DP show any of the above?