First, ARS doesn't cause most of the symptoms you describe (like nasal congestion, postnasal drip, small nodes in the neck only, symptoms of an ear infection). Geographic tongue has a hundred causes, almost all more common than HIV. Absence of fever is itself strong evidence against ARS.
Equally important, despite your concerns about your own behavior, it sounds like you had pretty consistent safe sex, especially since the anal sex apparently was always condom-protected. As you learned on the community forum, from Teak and others, oral sex is low risk, despite what you seem to believe. It is wrong that opinions on that "vary widely" In fact, they very quite narrowly -- from those who believe there is no risk to speak of and those who believe there is some risk but that it is very low. Nobody argues that oral sex in either direction is a high risk activity; indeed, most experts specifically include unprotected oral sex as a safe sex activity.
Do I think you should be concerned? From a medical or risk assessment perspetive, definitely not. But that's beside the point. The fact is that you ARE concerned. So have an HIV test. Enough time has gone by for completely reliable results. Given all you describe, you can be sure it will be negative.
Finally, good for you for wising up. Obviously, having multiple casual sex partners isn't a good idea. That said, you are using condoms consistently for anal sex, which is excellent. The other thing you need to do, should have any relapses and resume such behaviors as last summer, is "do ask, do tell": always ask partners about HIV status and share your own, before having sex, even when safe sex is planned. (Condoms can break, and sometimes condom use is forgotten at the height of arousal.)
Stay safe-- HHH, MD