This is a reasonable request , right?

I was rear ended in December 2024 and got a pretty acute form of whiplash. My car was total loss and I've been going to a chiropractor for the pain. I also get very hypervgilant in a car at a red light, thinking someone will rear end me. My lawyer said if I want to include it in my claim I need to have my therapist write a bit about my fear, to prove in claim. I've even had two bad dreams about being hit again.
I asked her to possibly help me , that I experience PTSD when at a red light, and she was very reluctant to say she'd help. She said "That's hard to prove, and just focus on physical aspects. " Then changed the subject essentially. I was really quite in a slight daze wondering why they couldn't help me when I've talked about my fears of the accident several times? Is it a huge process for a therapist to provide information for a client in a collision? 🤔