HI, thanks for using health care magic
The rapid tests detect the presence of antibodies
in the body.In some persons these antibodies take a few months to form which is why there is a window period of 3 to 6 mths.The window period is the time taken for a test to detect the presence of a disease if it is present.
Since you did the test close to the end of the window period it is likely to be truly negative but it is understandable to be concerned.
To allay your fears , you should consider repeating the antibody test after the 3 mth mark or you can do the other HIV test
which checks for the virus itself (because of this , its window period is 21 days )
I hope this helps and wish you the best