Which name should we use as my family name if all of my legal documents are still in my maiden name?

In the marriage-based adjustment of status application process, generally a wife may select to use her legal last name or to adopt her husband's last name as her own. This is true regardless of whether the wife may have used her husband's last name prior to commencing the application process and all of the existing records reflect the wife's old last name. It would be wise for you and your husband to consult with an immigration attorney who, after learning all of the relevant information, could advise about eligibilities, options and strategies to attain your goals, and who then could offer legal representation in the often complex application process.