Hello First of all reading carefully so that you will understand better. Although HIV can be isolated typically in low titers from SALIVA of a small proportion of infected individuals ( mind it a small proportion ) , there is NO convincing evidence that SALIVA can transmit HIV infection , either through kissing or through oral sex or other exposures., such as occupationally to health or sex workers . SALIVA contains endogenous anti viral factors ;among these factors, HIV specific immunoglobulins of IgA , IgG and IgM isotype are detected readily in salivary secretions of infected individuals. However EXCEPTION can t rule out ,but there is minimal chances of getting HIV infection through this rout. Hope this will relieve your stress . 2nd point is that almost more than 3 weeks passed after your sex encounter ,if you have any doubt get in antigen antibody NAT ( nucleic acid amplification test) . Good luck.