Getting married is a big life change. No wonder you are stressed. And when stressed, we can be panicky and have that flight or fight response. Not full one but in general and when we have this, we really have a harder time thinking. This is proven. So, you know you aren't at risk. You know that with your job comes safety things for HIV and testing that you can easily do. And you realize that your fears are irrational and have really nothing to do with HIV. So, work on coping mechanisms. Breathing exercises, medication and exercise. If this lingers though after the marriage ceremony, see your doctor to discuss. good luck and happy wedding day!
April 18 isn't that far away. You can make it until then. You know you don't have HIV, and of course as a nurse you know better than any of us how to get tested probably for free, but it's pretty clear the anxiety is an issue no matter what. Exercise, meditation, breathing exercises can help you in the meantime. You also don't say whether psych means a psychiatrist, which means medication, or a psychologist who specializes in therapy for anxiety -- most of them don't.