How To Confirm HIV Infection?

Hello,
I have query regarding HIV.
I had sex before 2.5 month almost before 3 month (80 days before).
I had sex with one married girl. She is married before 2 years. Her relation with her husband is not good. Once she came to my town and we travel many places and at last day we done sex.
I have not any knowledge of her HIV status. After many days I had found she had many orkut male contacts (Not normal male but she Is continuously adding male friends and she is also contact me from orkut). But her married family comes from strong relation means in her family no girls talk outside.
She had live alone for almost 1 year in same city from separate of her husband so I am worried about this because may she is relationship with other. She is English medium teacher and like study too much.
I had sex that’s my big mistake. But actually I had fallen in love with her. Anyway after sex I had some headache for one week may be because of Cold environments and also 102 degree temperature fever gone in two days after taking injection from doctor.
After that no many symptoms found but in last week I horribly worried about HIV. I had read articles on internet. She had headache for long time, fever for long time, back pain for long time and also too much weakness. Because of her symptoms I am to much worried about HIV. I told her but she said me that I dont have HIV.I know all the HIV symptoms which don’t I have.
But I am too much worried so do HIV test after 79 days of sex. Below are details.

SPECIMEN BLOOD
INVESTIGATION HIV I & II antibodies
TEST METHOD
CMIA

RESULT(S/CO)
NEGATIVE (0.12 S/CO)

REFERENCE VALUE (S/CO)
> 1.00 REACTIVE
0.90 TO Note 1: Architect HIV Ag/Ab combo assay is a chemiluminescent microparticle immunoassay (CMIA) for the simultaneous detection of
HIV 1/HIV2 antibodies and HIV p24 antigen in the human serum or plasma.
HIV Ag/Ab Combo is used as an aid in the diagnosis of HIV infection.
Limitation:
* This test does not discriminate among HIV 1 antibody, HIV 2 antibody or HIV p24 antigen.
* A negative test result does not exclude the possibility of exposure to infection with HIV1/2
* Presence of HIV antibodies and p24 antigen is not diagnostic of AIDS.
* It is recommended that repeatedly reactive specimen be investigated by supplemental test such as Western Blot.
Note 2:
HIV testing follows the NACO guidelines
Note 3:
It is presumed that the patient counseling is done at the referring centre for received samples. The test results obtained relate only to
the sample given / received and tested. A single test result is not always indicative of a disease; it has to be correlated with clinical
findings.

From above I am Negative. But I had read there may be possibility after three month.
So can you suggest me what I have to do? How much possibility after 3 month for HIV? I am internally strong. But I m too much worried about HIV. I am unknown before two week for HIV. Suddenly in my mind had strike idea about HIV.
At this time I don’t have any symptoms But according to Science how much possibility for me to have a HIV?
Thanks a lot.

I used Condom bt Once it's come out 3/4.....