Thanks for your question.
HIV is definitely diagnosed only by the tests and not by the symptoms, since every symptom can have a number of possible causes.
Therefore don't worry that these symptoms are due to HIV, and make yourself anxious. This will only increase your present symptoms.
The PCR test is beneficial for early detection and is able to detect HIV as early as 7 to 14 days. Basically for HIV infection, the period after exposure until virus is detectable by methods such as PCR is called the "eclipse period," and the average eclipse period for HIV infection is estimated to last 10--15 days but can be longer.
Please refer to the below web-link, according to which, the NAT test is able to detect HIV RNA as early as 7 to 14 days:
So the RNA test which detects the HIV virus directly is a very sensitive and accurate test and the time between HIV infection and RNA detection is 7 to 14 days.
But the point that I need to emphasize is that even though based on the present tests you are negative, still the utility of HIV RNA test for screening of HIV is presently not known and getting an antibody test done after 3 months of exposure is recommended.
However in your case the likelihood of getting infected with HIV with your exposure is essentially non existent, but still get the test done as according to CDC even without exposure all adults need to have an antibody test done at least once.
Regarding your wife she needs to consult her doctor now to know the cause for her symptoms which is likely due to the cold and and an acute episode of bronchitis. Especially since she is pregnant get her seen by her doctor as soon as possible.