How do I know that you are HIV

 
The _only way_ to know if you are HIV positive is to undergo a blood test. There are _no symptoms_ that HIV infection causes. In the later stages, other infections caused by the low immunity can give rise to symptoms of that infection. So if you suspect that you may have had exposure to HIV, you can take a blood test to be sure of your status. There are self testing kits available which use saliva as a sample. However, these tests have a higher rate of false results than the blood based tests. The good news is that if you do turn out to be HIV positive, there are excellent medication (ART) available these days which can help you live a healthy and active life.