Wow, you are playing with fire. On the one hand, you seem dedicated to safer sex -- it is clear you intend to use condoms for high risk encounters but do not consistently do so. For you to catch rectal chlamydia, there obviously had to be a lapse in sexual safety. And now you bottomed with a new, casual partner. Although it is logical to assume the risk of HIV/STD transmission is lower without ejaculation in the rectum, unprotected anal sex remains an exceedingly high risk practice with or without ejacuation. Most likely your partner wasn't infected, since most people don't lie about HIV status when asked directly.
I'm also puzzled that your rectal chlamydia was diagnosed in July and you only recently made an appointment to get treated for it. What the heck is that about? Did you inform your rentboy partner that you had rectal chlamydia and that he was obviously at risk for that STD by having unprotected sex? If so, that was highly irresponsible.
So for the long run, your anxiety is entirely appropriate. If your sexual choices continue as they have, you can expect to catch HIV someday. However, it still seems unlikely you were exposed during the event 3 weeks ago. To be maximally safe, you should be tested for HIV, and 2 months (December) would be fine; if that is negative, you can be very confident you aren't yet infected.
However, as long as your sexual lifestyle remains as it is, I suggest you not worry about timing your tests with particular encounters. Just have a routine HIV test (as well as STD testing) at regular intervals, like every 3 months.
But most important, please think seriously about your sexual choices. I'm glad you realize change is needed, as reflected in your username. Still, you need to put your intellectual understanding into action. There simply is no excuse for any man having sex with other men without sharing HIV status and using condoms every time, no exceptions, for anal sex. This goes double for people in urban areas with especially high rates of HIV and STD in gay/bi men, like San Francisco (which I infer from your username). And please get that chlamydia treated, and also phone your rentboy partner and tell him to get treated for chlamydia, if you didn't tell him previously.
Regards-- HHH, MD
Stupid is not limited to sexual practices. The reason I waited so long from test to appointment is that I lost (misplaced) the card with my code and only found it three days ago. There was no lack of motivation. I'm just a putz.
OK, I understand the timing. Still, it's a rather long gap from testing 10/29 to a treatment appointment in December.
Fear is often thought to be a great motivator, but in fact it is a rather weak one. Each year millions of people who fear HIV or other STDs nonetheless become infected. I'm not knocking your motivation, just want you to understand that actually following safe sex practices on 100% consistent basis isn't necessarily easy. I don't want you to take the responsibility casually; guard against overconfidence about it.
Thanks for the holiday wishes. Same to you. Keep safe.
Thank you for the quick response. One point of clarification: The results of the positive test for chlamydia was taken on 10/29/08, which covered all sexual activity since July. As you stated in your response, the encounter in early October probably did it for chlamydia, although I had some symptoms before the last encounter. Finally, I made an appointment for treatment as soon as I got the test results. Stupid, yes. However, even us dummies can be reformed! Fear is a great motivator. Best to you and your loved ones for the holidays.