Based on the information provided let me answer your questions one by one.
(ANS 1). Risk of being exposed is present but since you got 2 successive test negative it seems you have very low risk now, but not absolutely out of the trap. As normally the P24 test comes positive in between 2-8 weeks and only 2 week have passed so just a slight changes of having false negative result.
(ANS 2). Now as explained in "ans 1" the negative test cant be relied upon completely as its falls in to the zone of 2 weeks from exposure but its better to take p24 test again around 8 weeks from the exposure just to be 100% sure of the result.
(ANS 3). YES you will need one more test at the end of 2 months period, just P24 will be enough to rule out any residual chances of the infection present.
(ANS 4). No further consultation is required at this time till the next test is done after 3 may 2013, if that indicates any problems (mostly nothing to worry at this point) the can contact any physician of your choice who has a medical degree.
Normally post exposure prophylaxis is given in case of cut or blood contact, But if needed to have such precaution may need to contact physician.
Make sure to use protection, as its very risky business.
stay calm nothing to worry mostly one exposure is less likely to do harm and you are taking all necessary precaution of getting tested for HIV
HOPE I have addressed all your concern.
Dr. JAY PATEL