Sorry, I really cannot help much. Your herpes tests prove you are not infected with HSV-1 or -2. The IgM HSV tests are totally useless, whether positive, negative, or indeterminate, and repeat testing will not sort things out further: the IgG results are all you need and you can be 100% certain HSV has nothing to do with any symptoms you have had.
NGU sometimes recurs, and mostly doesn't mean anything serious; in fact, such recurrences might not be due to infection of any kind. Certainly it is not a significant risk to your health (no cancer, no infertility, nothing) or to that of a future sex partner.
You have been under the care of a GUM clinic, a dermatologist, and a urologist. Follow their advice. I can add nothing further.
Good luck-- HHH, MD
Check with your own provider(s) about whether it is OK for you to have sex. From all you describe, I see no reason not to do so.