Even if there was blood involved while you kissed someone, there is no risk associated with this event. Injesting infected fluid is not an effective route to HIV transmission. Saliva and gastric acid inhibits the virus.
Newer generation of HIV test are very sensitive and false positives do happen a few times. Specificity of these tests are said to be at 99.6%, out of 1000 times tests are run 996 would be accurate result with 4 result being false positive.
False-positive test results can occur due to technical issues associated with the test or biological causes.
If the aforementioned was the only 'exposure', you need not worry about infection.
This answers all of your HIV questions, and if you can think of any more just reread about the 3. You had zero risk therefore testing is irrelevant to your situation because you had zero risk. HIV is a fragile virus, which is instantly inactivated in air and also in saliva which means it is effectively dead so it can't infect from touching, external rubbing or oral activities. It doesn't matter if you and they were actively bleeding or had cuts at the time either because the HIV is effectively dead.
Only 3 adult risks are the following:
1. unprotected penetrating vaginal with a penis
2. unprotected penetrating anal sex with a penis
3. sharing needles that you inject with.
The only way to get HIV is if you did one of the 3. The situation you describe is a long way from any of these 3.
Even with blood, lactation, cuts, rashes, burns, etc the air or the saliva does not allow inactivated virus to infect from touching, external rubbing or oral activities. The above HIV science is 40 years old and very well established, so no detail that you can add to your encounter will change it from zero risk. Doctors have calculated the risk from what you describe to be less than that of being hit by a meteor, therefore no one will get HIV from what you did in the next 40 years of your life either.
If you didn't have one of the 3 then you are just worrying about your own hiv theory - which is unrealistic for you to think that can become reality - so you should move on back to your happy life instead.
The first step to peace is to quit googling for death cold turkey because you aren't a medical professional and don't know how to read technical medical articles or to determine when you are reading something that is theoretical which has never manifested in 40 years of history.