There are two basic immune systems: innate and adaptive. In some cases the innate immune system clears the infection before the adaptive immune system produces detectible levels of antibodies.

https://en.wikipedia.org/wiki/Innate_immune_system?wprov=sfl...

Sorry, I'm aware of that in general. I was wondering in this case. I suppose that's possible for people who don't fall sick (I assume that's why low viral load means you can get exposed and not get sick?) but OP was quite sick.

I think it’s unlikely that’s it for someone seriously ill for an extended period.

some people are recovering through other responses, including t-cell response, etc. I don't have the academic experience, the clinic experience, or his specific medical history, so I can't speak specifically. I do recall lots of papers at the beginning of Covid talking about high t-cell responses in patients without a lingering anti-body response. That all could have been early science based on poor data as well though.

Based on the information provided it seems highly unlikely the OP had covid.

It isn't impossible but the lack of antibodies is just one further data point. Most people who recover have positive antibody tests.