i took the test because i had sex with a masseuse for a few times throughout 1 month or so. i always used a condom but one time it came off and i believe i was exposed for a few minutes at most. but my main concern is i dont know her background and if she is hiv positive. i took the hiv test at the 7.5 weeks post exposure and it was negative. i asked the nurse/obgyn if i needed to follow up but she says i dont. she says it detects hiv after 28 days. should i be worried if the test wasnt able to detect antigen or antibodies at the time of testing (7.5 weeks)? i heard that at a certain time frame, p24 antigens are lower in level. please help.