Nothing wrong you mentioned about your imagination. Imagination is a normal and natural process. Problem occurs when it excessively occurs and impairs someone's life's  normal routine. Several time psychiatrists themselves suggest to imagine a situation and how to act in those situation in imagination as a treatment in social phobia. For your problem it is essential to know in detail whether any perdonality problem or any obsessive phenomenon  is responsible for your concern. So plz consult a psychiatrist at the earliest.