The sexual encounter you have mentioned is of low risk. And you have a 85 day negative test report (most likely antibody based ELISA test). So we can reasonably conclude that you are negative of HIV and safe.
However with this you can only be 99% sure. For absolute surety you will need to repeat that test (90 days repeat is good enough) . The test is available free of cost at Government run hospitals. Once again for all practical purposes you are safe and HIV free.
Hope this helps
Please feel free to ask followup questions