Never has cpx as child, had 3 vaccines as adult but no immunity. trying to conceive. should i get vaccinated again before conceiving? what're my risks

I don't think so: The usual ELISA antibody test for chicken pox/varicella is not especially sensitive; some people are immune but the test remains negative. A more sensitive test, latex agglutination might detect a low titer antibody. If you truly have no antibodies after 3 doses of vaccine, you are presumed susceptible and should avoid exposure to chicken pox when possible. There is no data on more than 3 doses.