As I read your reply, it appears that you are assuming the worst and that this IS genital herpes. That is NOT my message to you. I think that I would be misleading you if I did not acknowledge that some of the symptoms you describe are somewhat (but not very when considered in context) suggestive of herpes but the likelihood that this is herpes remains low. Further, acknowledging your comment regarding guilt and anxiety, I need to tell you that it is quite common for us to find that guilt and the resulting anxiety over a possible STI can amplify awareness of what are otherwise normal sensations and lead to spiraling anxiety and concerns. Regarding your specific follow-up questions:
How would your risk assessment change if there was brief penetration of just the penis tip for a couple of seconds?
No, my assessment would not change at all. Your tests are strong evidence that you did not acquire the most common STIs from your casual partner.
I understand due to the recurring nature of my symptoms, HSV is a likely cause which needs to be ruled out?
Given your anxiety and level of concern, it is my sense that if you do not rule HSV out, you will continue to worry.
With recurring HSV outbreaks, is it usual for symptoms to occur at multiple locations, for example anal symptoms and penis symptoms at the same time? I have read about Herpes outbreaks being unilateral or something like that.
HSV recurrences tend to occur in the same place time and again. Each person has their own pattern. For you to be having simultaneous recurrence in two locations without lesions would be quite unusual. I have never seen such a thing.
I have read many accounts online of people who report similar symptoms and it is believed that bacteria can be deep in the prostate which means urine testing is not conclusive. Have you heard of this?
Prostate infections may be difficult to diagnosis but typically there is some evidence present in the urine. Your follow up question however does bring to mind a genital discomfort syndrome called the Chronic Pelvic Pain Syndrome or CPPS. This syndrome which is NOT an STI. is well described on Wikipedia
I hope this information and perspective has been helpful. This is the 3rd response to your questions, thus, as per Forum Guidelines this thread will be closed shortly without further comment. Take care. EWH