You're fine.

Go about your life and chalk this up to experience. Millions upon millions of HIV tests are run a year. If there were gliches in the system, a whole lot of people would turn up positive after having negative tests. This just isn't happening.
Worry about having a fatal disease, even after tests prove you wrong is a form of OCD (obsessive compulsive disorder). Please get help for that if you can't seem to get past this. Good luck to you. YOU ARE NEGATIVE--REJOICE-BE HAPPY!