No, what she said about your Other Specified Trauma or Stressor Related Disorder (also called "partial PTSD", "subthreshold PTSD", or "subsyndromal posttraumatic stress syndrome") was:
The legal wording required for these medical opinions is confusing. The part in parentheses is usually easier to understand, i.e., "50% or greater probability" in your case. So, she's saying several things:
Your current posttraumatic stress symptoms don't quite meet full criteria for PTSD, but they do meet the criteria for subthreshold PTSD, which in DSM-5 terminology is called Other Specified Trauma or Stressor Related Disorder. (DSM-5 is the diagnostic guide mental health professionals must use in C&P exam reports.) She essentially said "Yes" to the question, "Was the veteran's Other Specified Trauma or Stressor Related Disorder incurred during military service?"
She said she does not think your more recent depressive and generalized anxiety symptoms are related to your subthreshold PTSD, i.e., only the amount of social and occupational impairment caused by your subthreshold PTSD is compensable. She estimated that half your problems are caused by subthreshold PTSD, and half are caused by whatever she put for Diagnosis #1 (you did not include that part of your report in your post, so I don't know what that diagnosis is).
She checked off the summary statement ("Occupational and social impairment with occasional decrease in work efficiency...") that corresponds with a 30% disability rating.
You did not include which items she checked off on the "Symptoms List" (Section II, Number 5 of the report). The VBA Raters focus on that more than the summary statement.
If the items she checked off on the Symptoms List also correspond with the 30% disability rating (you can find which symptoms correspond with which disability rating levels in the General Rating Formula for Mental Disorders - search the board, I know it's posted in at least one or two places on this site), then overall that's your level, BUT she said that your service-related condition (subthreshold PTSD) causes half of that impairment and the other half is not service-related. So, theoretically, you would qualify for a 15% disability rating, except that there is no such rating for mental disorders (it's 0%, 10%, 30%, 50%, 70%, or 100% only).
In most cases like this that I've seen the VBA Rater gives the benefit of the doubt to the veteran and would rate at 30%. But if you want more precise guesstimates regarding your probable disability rating, you need to post that Symptoms List because if she checked off a whole bunch of symptoms than you're likely to receive a higher disability rating.
Also remember that the C&P exam report is important, but it is not the only basis for your disabilitiy rating. The VBA Rater will also review your medical records, especially mental health treatment notes and primary care notes; any statements you or family members or friends submitted; your service medical records; and any other relevant evidence. For example, the VBA Rater might decide that there is solid evidence that all your mental disorders are service connected, i.e., the Rater disagrees with the C&P examiner's opinion on that point. The Rater makes the decision.
Good luck!
All the Best,
Joey