I was frightened as a 12 year old by a friend who was to meet me  at night in a remote place.  She jumped out from behind a bush and put her hands around my throat and just hollered loud .  I jumped of course and cried , wet my pants nad went home mad.  I get startled easily even when my husband comes into a room unannounced.  Do I  have ptsd?  I am now 73 yrs. old.  All this started after the fright.
Greetings ! Well your case scenario does indicate that you have elements of PTSD, but it cannot be completely described as PTSD since for PTSD the traumatic event which starts this condition needs to be too severe and devastating for the person to create a lot of stress in the persons' life, in your case you more suitably fit within the diagnostic parameters of a condition called as Situational anxiety disorder where the situation that evokes anxiety and Chat Doctor.  The fact that it all started when you were a 12-year-old just shows the age of onset of this condition, but it cannot be defined as PTSD as the emotional trauma that you were exposed to was not that catastrophic and unprecedented that is usually associated with PTSD. I will suggest you to seek CBT (Cognitive Behavior Therapy) from a clinical psychologist to work on your situational anxiety. I hope this helps. Regards.