Welcome to the forum.
I hope I can help you get past your worry about HIV. The chance your partner had HIV, and the odds you caught it even if he did, both are extremely low. Among men like your coworker, under 1 in 1,000 have HIV; and for each episode of unprotected vaginal sex with an infected male partner, the average transmission risk for the female partner is about the same, 1 in 1,000. Combining both of these facts, the statistical chance you caught HIV is in the ballpark of one in a million.
Rather than worrying about time to reliable testing, my recommendation is that you have a conversation with your coworker and suggest that the two of you go together for HIV testing. You may find that he's as worried as you are! And even if not, he'll probably understand your concerns. If you both have negative tests, you'll both know neither is at risk from the other. While you're at it, include testing for other treatable STDs, i.e. gonorrhea, chlamydia, and syphilis. The risks for these also are low, but a lot higher than for HIV.
If your partner refuses or you can't work it out and you're the only one tested, I recommend waiting until 4 weeks have passed, then seeking out a clinic or doctor that offers the duo test (for both HIV antibody and p24 antigen) -- the results will be conclusive at that time. Also have a urine or vaginal swab test for chlamydia and gonorrhea, and a syphilis blood test. (Or you could go at any time for the gon/chl testing -- which is accurate any time more than 4-5 days after exposure -- and put off the HIV and syphilis tests, since the chance of either of these is virtually zero.)
The main thing is to not panic and don't be overly worried. Don't confuse your apparent guilt or shame over a sexual decision you regret with STD/HIV risk from that event. They aren't the same. Deal with the former as you need to, but stay relaxed about infection risks, which are miniscule.
I hope this has helped. Best wishes-- HHH, MD
Thank you so much. I am having a hard time finding the duo test in Denver. Is there a website I should be using to find it? Is it really $250-$350?
So I took a duo test yesterday 6 weeks after initial exposure and it did come back negative. I have to admit there was a second encounter 15 days ago, with the same man as before. Do I need to retest after 4 weeks from that exposure (May 14th) to 100% rule out and HIV transmission?
I see no reason for testing and never did. But since you obviously have doubts about your partner's STD/HIV status and hor sexual safety, rather than testing yourself repeatedly, I would suggest you speak to her about being tested. If she's negative, you'll know you're not at risk.
Thank you for your response. So it sounds like it would be unnecessary to have any more testing done. Although just a correction, I am the female in this circumstance, my partner was male.
For sure no more testing is needed. Sorry I mixed up your genders -- I had it right in the earlier part of the discussion.