Welcome to our forum. Your concern is one that we hear frequently on this Forum, in particular from persons who have been searching the internet on this topic. Unfortunately, there is a lot of erroneous information which is all too readily available on the internet.
If your HIV tests were taken more than 8 weeks after your exposure, you should have complete confidence in the result. In North America the production and conduct of these tests is very tightly standardized and regulated so that a person should have virtually complete confidence in any single test result and if you have had three tests performed at two different labs, your results are absolutely reliable.
Putyour fears aside, there really is no reason for you or any other normal/average person to worry. EWH