Has anyone used the COVID-19 Antibody Test (blood test) to track antibodies from vaccine?

I asked my Doctor to run mine while I was there for shits and giggles and it came back negative. I was last vaccinated in October and December when I received Novavax (restarted my series)

I’ve heard they only lasted for a certain time but with Covid numbers going through the roof right now and the government dragging their feet on approving the new vaccines I’m scared. I’m immune compromised and I I have a baby with a heart condition.

I’m thinking once the new vaccines come out I’m going to get the test done every month. You can ask for it yourself without a doctor but then you can’t use insurance . I’m just kind of interested to see when my potential immunity disappeared.