I have struggled with such fears, particularly with my psychoanalyst many years ago. Part of my trauma actually related to not being believed originally, so that fear does haunt me sometimes. However, my therapist has been warm and affirming throughout our time together. She clearly believes me, logically and emotionally. I think that's invaluable, and can only encourage you to speak to your therapist and hopefully confirm it again until it sinks in. I have been learning.... it is okay for me to need reassurance, okay to ask the same question more than once. I wouldn't do that at work or other relationships really, but I make an exception in therapy.

Keep in mind though... while it is important to have faith in your perceptions, don't worry too much about those grains of salt- it is only human that many things affect our perceptions, don't expect anyone, including yourself to be 100% objective. You'll see things differently if you're tired, hungry, angry, sick, stressed, anxious etc. Consider witnesses to car accidents, who often "recall" different colors or models of cars..... perfect perception isn't everything, but you and your therapist can hopefully trust your perceptions and feelings at the fundamental level. What really matters is how you feel and act.