Hi,
It's very possible to have PTSD from medical conditions/medical experiences.
My initial traumas were in childhood; yet, I continue to have trauma from medical conditions.
Not every mental health professional realizes the trauma potential via medical conditions/medical traumas.
It's also possible you were drinking to self-medicate for the effects of earlier life trauma, as well.
Keep on talking to your therapist. Let your therapist know you feel this way and would like someone to look at PTSD seriously. Get a second opinion if you'd like and can swing it.
Keep posting here if it's helpful to you.

WC