There are many details in your question that don't matter. The HIV RNA PCR tests are 100% conclusive any time 11 days or more after exposure. Your negative results at 20 and 26 days show you do not have HIV. Nothing else matters -- not the amount of risk at the time of exposure (which in any case was near zero risk for HIV), not your symptoms, not any of your other test results.

Those comments pretty well cover both your numbered questions, but to be explicit:  1) "Is it HIV?" Nope. 2) "Could it be that all these tests are false negatives, as it might be within window period." No; and both your PCR RNA tests were well beyond the 11 day "window period".

2. Is there a chance that this is HIV-2, which might have low viral load and go undetected by the RNA test I did (sorry if I am still overthinking this)

3. Could Rhinovirus (Common cold) that I got tested positive for be the culprit here and then my anxiety just made it seem 100 times more terrible?

4. My doctor also suggested to do the HSV-2 test one more time in 3 months along with hiv 4th gen test, does this mean there is a possibility of HSV-2 test (blood test) being a false negative after 25 days and should I still do hiv tests?

5. I also would love to know, if you think I should consider testing for Hepatitis diseases, and maybe do syphilis test in 90 days?

2. Some of the RNA PCR tests now include HIV2 and well as HIV1. But your antibody tests also have been negative, and they cover HIV2 -- and prove HIV2 is not he cause of your symptoms. And again, you had a zero risk exposure for HIV.

3. I missed your positive rhinovirus test. It could be causing some of your symptoms, yes.

4. I disagree with any advice to test for HSV2 in this situation. There is absolutely nothing in your symptoms or the nature of your exposure that fits with herpes.

5. You were not at risk for hepatitis. Sexually transmitted hepatitis B virus (HBV) is now rare because of widespread immunization (and you are immune if you were vaccinated). And contrary to popular belief, hepatitis C is not a heterosexually transmitted STD. 

A few days after that exposure, while I didn't have any symptoms and was unaware I had contracted something, I had a protected sex with another girl, who I just talked to again and she said she had developed some flu-like symptoms, pain in thigh muscles, and now has some pimple/foleculitis/acne looking things showing up on her body in arms and legs mostly that don't itch initially but dry up and shed slightly in 2-3 days and then get slightly itchy. She had also tested HIV-1 RNA 12-13 days post our encounter negative. But I am now very scared that I might have given her HIV, please help! I can live if I have it but if I passed it to someone else, it will be unbearable for me. Could her symptoms be Syphilis, HSV or something else? What else should we test for?

Perhaps you would also like to know this:  In the 21 years of this and our previous forum, with thousands of questions from persons concerned about exposure and infection with HIV, nobody has yet turned out to be infected. You will not be the first. If and when it finally happens, it will be from a genuine high risk exposure, which you did not have. (Think unprotected anal between two men.) And it also will not include impossible false negative test results!

As you expected, that concludes this thread. I hope you're finally able to accept the professional, expert, reasoned, science-based advice you have had, probably from your own doctor(s) as well as this forum. Move on without further worry. You're fine.

Best wishes and good luck.