Advice!!

I have a phone call with the gp tomorrow, I’m literally terrified i cannot handle phone calls but ive heavily suspected that i am autistic for 5 years now! My therapist also a few months ago brought up her believing i am also autistic, she has helped me finally muster up the courage to speak to a gp, however, historically my gp has been awful with understanding that ive needed support with my mental health and have dismissed me- i am trying to write a script right now but my mind has gone blank! My therapist has made a list of things she has noticed about me that will help support me while speaking to the gp but im just worried it wont be enough? If anyone could give me any advice id really appreciate it! :-)