Yes, that's why I'd love to get an antibody test right at the end of the isolation period. If that's impossible, that might be a reason to do the RT-qPCR test, but in that case it's probably still optimal to do the test after a presumed incubation period rather than immediately to reduce the chances of a false negative.

You want all the kinds of tests. I'm pretty sure I had coronavirus in mid-March (I live in NYC), but seeing as how there were no tests available at all unless you were hospitalized at a minimum, I just suffered through it in home isolation. By the time antibody tests were widely available nearly two months later, my result came back negative. A swab test at the peak of my symptoms would have been more conclusive (had it been available). A lot of people who had it earlier on are already testing negative for antibodies. And now it's at the point where I'll never know for sure. I really wish the testing (all kinds) had been available in mid-March, so I'd know for sure. Now that the testing is much more available, you'd be crazy not to take advantage of it.

What would knowing for sure change for you? As you correctly noted, antibody levels seem to decline fairly quickly, so it's not like you can rely on immunity. It's true that there's a long and growing list of complications associated with C19, but I don't know of a single one where the diagnostic or therapeutic options change in any way based on whether you had C19 or not. In theory, if we actually had a thorough understanding of the mechanisms (and probabilities) of various complications after C19 it would affect the process of diagnosing them, but we're a very long way from that.

It bothers me greatly to not know things for sure. I can't even tell this story without having to put a giant caveat on it.

This really wouldn't bother you??? You really wouldn't mind not knowing?

One giant reason that knowing for sure would be helpful is knowing that you're less likely to get reinfected, and likely less likely to have serious effects if you do end up reinfected, if you previously had it (even if blood antibodies have faded, your T memory cells may still help you out). This might change your behavior going forward.

Technically, I'm in a slightly similar position to yours as I had an uncommonly annoying respiratory infection during the last week of February (I am not in a disease epicenter, however, so my Bayesian prior is much weaker). I don't believe having a positive (or negative) test would meaningfully change my behavior or medical decisions and I don't feel any significant psychological discomfort about it. That said, I respect that you feel differently, that's fair enough.

However, on the last point, I'm afraid that thinking might potentially prove quite dangerous. As far as I can tell (from closely following the medical literature, though I am not an immunologist and don't claim any authority on the subject) we really have no idea as to how quickly immunity decays, every single cellular immunity (T cell) study I've seen is extremely limited methodologically and we have no clinical evidence whatsoever to suggest that reinfections would have a milder course. If that turns out to not be the case, people who behave incautiously based on their test results might significantly endanger themselves.

>There are lots of potential long-term health effects to the virus

This has been repeated ad nauseam but there has been no proof of any long term or permanent side effects from COVID, especially for asymptomatic cases. There are a few anecdotal cases but nothing concrete. Yes, if you get a bad case of COVID with a harsh pneumonia, that will result in a lower lung capacity for a while but that's always what happens after lung damage. But to say "lots of potential side effects" is bordering on disinformation.

It's been 7 months now, we would have known by now. It makes absolutely no sense to keep pushing for the "we don't know a lot about the virus so we can just assume the worse and there's no way to prove otherwise" arguments after 5m+ infections and still no evidence even with almost every scientist and every doctor in the world being focused on COVID right now.

There is plenty of proof of long term and potentially permanent side effects, including some that are uncorrelated to disease severity. It's also true the relative prevalence of such side effects is far from well understood, but that is not a valid reason to dismiss the concerns outright. To counter your statement regarding "no evidence", here's just a few recent studies that provide such evidence (please note that this list is extremely far from being remotely exhaustive):

1) https://academic.oup.com/brain/article/doi/10.1093/brain/awa... "The high incidence of acute disseminated encephalomyelitis, particularly with haemorrhagic change, is striking. This complication was not related to the severity of the respiratory COVID-19 disease."

2) https://www.nature.com/articles/d41586-020-01891-8 (on the possibility that C19 may trigger diabetes)

3) https://medicalxpress.com/news/2020-07-physicians-comprehens... (on the systemic effects of C19, many of the acute complications have chronic effects detailed in the full study if you care to read it)

4) https://www.thelancet.com/journals/lancet/article/PIIS0140-6... (on Kawasaki-like autoimmune disease in C19-infected children)

5) https://www.thelancet.com/journals/lanres/article/PIIS2213-2... (post-C19 lung fibrosis)

Note that I've only cited evidence from highly cited and peer reviewed studies. There's a lot more if you care to follow the medical literature, but I think I've proven my point. 7 months is actually extremely little time for proper epidemiological studies on long term complications, it will take years to understand the prevalence and relative risk factors. What is clear, however, is that there is plenty of clinical evidence for different kinds of long term complications that necessitate further research.