Some blood antibody tests can distinguish between viral induced antibodies versus infection induced antibodies.

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.