Small wedding dinner

Hi everyone! Hope everyone is keeping themselves safe during this difficult time. We decided to keep our date and instead of getting married in our original venue , we are going to have a dinner with immediate family and friends potentially. Most of my family members were flying from out of the country so we made the difficult decision to do something smaller this year and attempt to do the reception next year. My only concern now is if we are doing this dinner at a restaurant should we keep it between small like 10-20 guest ? Our initial number was 90 . I’m going to wear my dress and we will take some professional pictures. I don’t want to wait another year to be married as we want to start planning for a baby after we get married.
If we do this dinner should we send a wedding invitation by mail or an online will be sufficient ? I was planning to send the change of plans to the remainder of the guest letting them know we were postponing for now the big wedding as most of our wedding guest are at high risk and out of the country . Thank you for advance for the advice and wishing everyone the best during this difficult season