I used to think I wasn't worthy of a PTSD diagnosis either. In my case it relates back to a cardiac arrest. I literally died and was revived with a defibrillator. But because I was unconscious the entire time, I wasn't sure that PTSD was a proper diagnosis even though many symptoms led to that. I eventually sought some counseling and the therapist told me that even though the conscious part of my brain was not aware of what was happening, the subconscious part of my brain, that controls automatic functions such as heart rate, breathing, etc, was very aware. My subconscious experienced a trauma that was essentially a life or death struggle.
Like others have said, everyone is different and the source and degree of the trauma is quite different from person to person.