Welcome to the forum.
I looked at the discussion on the community forum. You had gnerally accurate responses. HIV has not been known to be transmitted by kissing, and even if your partner had HIV -- which probably she did not -- you are not at risk. The large majority of women who you might "presume is very high risk" in fact are not infected.
As for "hard to believe" that kissing or oral sex doesn't frequently transmit HIV, it has to do with saliva inactivating the virus (as you were informed on the community forum), plus HIV only being transmitted by exposure to large amounts of virus that have to come into contact with certain cells. Here is a thread that discusses the biology of HIV and STD transmission (see the follow-up comment December 14):
http://www.medhelp.org/posts/show/1119533
In addition, new HIV infections do not cause the oral symptoms you describe, at least not by themselves. Also, your negative rapid HIV test at 4 weeks really wasn't too soon. Although it sometimes takes 6-8 weeks for positive antibody test results, 90% of the time the test will be positive -- if someone has a new HIV infection -- by 4 weeks.
On the community forum, you said "a user posted to Doctor HHH about the man who believed he was infected by saliva from his HIV positive son". You misread something. I do not recall such a claim on this forum, and if there had been, I would have informed the questioner that such at thing was not possible. As you were told on that forum, you obviously cannot believe everything you read on line, wherever you read it. Nobody ever was infected in that manner.
If you remain concerned, you are free to have another HIV test. Assuming you have no other risks for HIV, you can expect any additional HIV tests to remain negative.
Really, mellow out. If you should turn up with a new HIV infection someday, it will not be from the kissing incident you are worried about.
Regards-- HHH, MD