Though I cannot know with certainty, your symptoms do not seem indicative of schizophrenia. Many people who own a Ouija board believe that they are interacting with spirits through the Ouija board. That is especially true among children and adolescents.
The other symptoms that you are concerned about occur when you are on the verge of sleep. Many people report having unusual sensory experiences during that time. Your experiences are more likely related to your drowsiness than being symptoms of schizophrenia.
It is important to know that because your grandmother had schizophrenia, it does not mean that you will develop the condition. The fact that your grandmother had schizophrenia increases the likelihood that someone in your family will develop it but that risk is relatively slight. Many scientists believe that schizophrenia has a strong genetic component but there is no known singular cause of schizophrenia. Many complex factors may be involved.
If you continue to be concerned about having schizophrenia, it may bring you peace of mind to be evaluated by a mental health professional. The advantage of meeting with a mental health professional is that he or she can review your concerns, gather a detailed psychosocial history and make a determination, with relative certainty, whether or not you have schizophrenia. Please take care.