Husband moved from the UK on a K-1 visa in January 2014. We married in March 2014 and applied for a green card. Conditional green card issued February 2015. We submitted a I-751 to remove the conditions in December 2016, and received the 1 yr. extension letter. Conditional green card expired February 2017. In October 2017, we got a I-551 stamp in the passport because we still haven't gotten the approved I-751 and the 1 yr. extension letter was expiring December 2017.