No Antibodies post Covid vaccination.

I got all my family vaccinated for covid. My mother was vaccinated with covishield whereas me and my wife with covaxin. We did an antibody test post the second dose. My mother, after 50 days of second jab showed good amount of antibodies. Whereas me and my wife after 17 days of second dose, showed 0 antibodies. None of us have history of covid infection. Me and wife took the vaccines on the same day from same location. The second dose we took frm a renowned hospital but both of us had no symptoms after that as compared to the first dose we took. I dont know if it is the vaccine genuinity or this is a common pattern seen with covaxin. Is the vaccine still effective if we dont have antibodies ? Will it give us protection? Does it makes sense to wait a little longer and repeat the antibody test?