The first and most reliable is to consult a psychotherapist or psychiatrist.
You can also ask people who know you how logically and clearly you express your thoughts, if your ideas seem to them very strange? Is it easy for them to communicate with you and understand you?
Think - do you have a lot of friends and, in general, communication with society? Or do you prefer your inner fantasy world?
Has any of the above changed significantly and qualitatively in recent years? How much does the state generally change in spring and autumn.
Have there been any cases of schizophrenia in the family?
How did you get this question?
The classic symptoms of schizophrenia are various voices in your head that tell you something or call for something.
But here it is worth noting an important point, if you understand that you are talking to yourself - then this is normal. The schizophrenic hears voices from outside.
We are all schizophrenics to one degree or another.
Usually, the clinical form is called personality split, in which a person does not remember himself in different states. It does not control itself and is not aware of some states. Not capable of full-fledged autonomous activity due to splitting