My exposure is I mentioned in previous Q, was unprotected anal with new female partner. 

It was only one exposure. 

This new female partner and on the same day we had sex, had HIV test, and again at 3, 6, 10 months. 

Me as well, had 4 weeks, 6 weeks, 3 months, 6 months and 9 months test

All test were negative. 

My Q,

Could she have HIV that is not shown on 4th generation test, i.e p24 is still not on the detectable limit for that long? And no Ab as will?

Second Q, I took prednisone 20 mg for 4 days, around 8 months of the exposure, would that change any thing?

Do you advise for PCT HIV test?

The only thing that worries me is that it can carry a false positive result. 

Can I forget about hiv and move on with my life?

Your advice is highly appreciated. 

"Could she have HIV that is not shown on 4th generation test, i.e p24 is still not on the detectable limit for that long? And no Ab as well?" No. False negative results do not occur at the times she and you were tested.

" I took prednisone...would that change any thing?" No it does not. There are NO medications or medical conditions that alter the reliability or timing of the AgAb (4th generation) HIV blood tests (except for HIV drugs themselves).

"Do you advise for PCT [PCR] HIV test?" It would be a waste of money, time and energy since it is already proved you do not have HIV. In the event of a future need for PCR testing, false positive results are very rare and this is never a valid reason to avoid PCR testing.

"Can I forget about hiv and move on with my life?" That is exactly what you should do.

I did PCR HIV test and was negative 

However I found that it test only for HIV -1

My Q, what is the max window-period for HIV-2 as I cannot find a source. 

Thank you in advance 

Your other blood tests were conclusive for HIV2 after about 8 weeks, and you were tested as long as 9 months after exposure. You do not have HIV2.

Perhaps it will also help you to know that in the 21 years of this forum and our preceding one, with thousands of questions from users worried about HIV, not one has been infected. You will not be the first. If and when it finally happens, it will be from a truly high risk exposure (which you did not have) and will not have had atypically negative test results.

That concludes this thread. Please note the forum policy against repeated anxiety driven questions. This being your second about this exposure and HIV testing, it must be your last. Such excessive questions may be deleted without reply and without refund of the posting fee. Thank you for your understanding. I do hope these two replies allow you to move on without further worry.