As far as I know, I haven't had it since, but did get the vaccinations. Do you (does anyone here) know if there is a test to see if you did have it, or does the vaccine response swamp that signal?
Probably not, there were nasty flu strains circulating then that are much more likely an explanation. It had already spread somewhat, but not enough to be a likely cause until March even in the areas with early outbreaks like Italy and NYC etc. Exponential growth means that not long before everyone has it, the vast majority don’t have it.
Edited: to be clear we both thought prior to the antibody test that it was covid!
However, antibodies decrease with time. (We have memory T-cells etc for long term immunity). Whilst I am not an expert, I would be very surprised if virtual induced antibodies were still detectable.
What you describe: it is very possible you had COVID, but it is also very possible you had a bad flu. There are other viruses too, like RSV, which used to be rarely mentioned, but at times can be nasty.
In contrast this test does not distinguish between virus and vaccine as the cause: <https://onlinedoctor.superdrug.com/coronavirus-antibody-test...>.
I don't have a better approach than checking the descriptions of individual antibody tests. But I know the distinction is real, because IIRC the ONS (statistics body) used tests which distinguished, when they ran their ongoing study.