Relationship since 2006, visited each other 5 times, filed for K-1 November 2012. POE September 2013, AOS filed November 2013, Green Card interview February 27, 2014 and AOS approved that day. Filed for removal of conditions December 3, 2015, ROC approved June 16, 2016. Filed N-400 for citizenship September 14, 2023 under 5-year presence.
There really is no better advice than patience. Although in Finland start preparing with all the necessary documentation that you need. Locating vaccination records from 3-4 different places is a Journey in itself