If I had exposure myself, I would only test once more for HIV at 12 to 14 weeks weeks, to confirm the 8th week result. However, a negative for HIV at 8 weeks is pretty good news in itself, and I am very optimistic that your next test will be negative as well.
Yes, it's very well known around the internet that the anti-bodies for HIV take a long time to show up. However, there are usually no statistics included to give the person reassurance that this occurrence is regarded as quite rare. Let me quote a user's journal entry here on Medhelp:
"If a person has transmitted the virus, they will test [positive], actually quite rapidly (usually within 6 weeks of exposure)." - "HIV: The Facts", by nursegirl6572:
http://www.medhelp.org/user_journals/show/88524/HIV-THE-FACTS
Regarding HSV, you should probably post a question on the Herpes forum regarding that. However, I can give you some insight to it here.
I've gone through a little HSV-2 experience myself, and I have found that false-positives are far more likely to occur than false negatives. In fact, I was misdiagnosed with genital herpes in May 2010. I paid out the butt for medication, until I found out I never even had it 4 months later.
When I had my HSV-2 testing done that concluded a negative result that 4 months following, my doctor said that a 6 week negative result was a conclusive result. She isn't your typical doctor, for she could have worked in internal medicine as a Diagnostician, but she chose to have a family practice instead.
By the way, I have had all of the symptoms you have listed here before, both of what you listed under what you suspected to be HIV and HSV. Itching, swelling, armpit pain, groin pain/tightness, I have had it all. Yet, I am not positive for HIV or HSV-2. I think anxiety might play a big factor in the symptoms you are experiencing, for I have quite awful anxiety myself.