I believe they are having another round of interviews early May. So I guess if you haven't received an email yet, then you aren't part of that batch.
We found out the end of August 2015 that we were getting an interview, and waiting for a date, they had interviews in September but my husband did not get that batch. He had to wait until February. We are almost at the 17 month mark.. I don't know what happens after that!
Hopefully, they start doing interviews more frequently.. since Mexico took over Dominican applications, they have had interviews in September 2015, February 2016 and now May 2016.. hard to say how often they will hold interviews, I hope you don't have to wait long.
Try applying for a visitor visa! A bunch of us from the February interviews were approved in November for visitor visas.. Having an interview is good reason for your husband to return to DR.. it worked for us.