so, being curious, I googled "covid antibody testing". came to the FDA site. Lots there, but here's an excerpt from the FDA:

"Recommendations for Health Care Providers

At this time, do not interpret the results of qualitative, semi-quantitative, or quantitative SARS-CoV-2 antibody tests as an indication of a specific level of immunity or protection from SARS-CoV-2 infection after the person has received a COVID-19 vaccination. While a positive antibody test can indicate an immune response has occurred (seroconversion), and failure to detect such a response may suggest a lack of immune response, more research is needed. Currently authorized SARS-CoV-2 antibody tests are not validated to evaluate specific immunity or protection from SARS-CoV-2 infection. SARS-CoV-2 antibody tests should be ordered only by health care providers who are familiar with the use and limitations of the test. For more information about antibody tests for SARS-CoV-2, see Serology/Antibody Tests: FAQs on Testing for SARS-CoV-2.
Be aware that vaccines trigger antibodies to specific viral protein targets. For example, currently authorized COVID-19 mRNA vaccines induce antibodies to the spike protein and not to nucleocapsid proteins that are likely detected only after natural infections. Therefore, COVID-19 vaccinated people who have not had previous natural infection will receive a negative antibody test result if the antibody test does not detect the antibodies induced by the COVID-19 vaccine. If you are considering antibody testing in vaccinated individuals, follow the Centers for Disease Control and Prevention’s guidelines for antibody testing. For more information about antibody test performance visit EUA Authorized Serology Test Performance."

So, based on this above statement, it does not appear that we (as patients/lay persons) can make a linear relationship between antibody test results and our protection from the virus.
Please enlighten me if you have more detailed and demonstrated data that would support getting this test. We all would love for it to be this simple but I'm not sure it is. So, we may be protected but the negative results may be making us think we are not protected.