I worked as a volunteer in Fiji Islands from 2012 to 2016. I flew back to Los Angeles on June 15, 2016 from Nadi, Fiji Islands with Fiji Airways. I did not go back to Fiji. I did not keep my boarding pass nor was my passport stamped on arrival by DHS in Los Angeles.
I applied for my Medicare coverage and the late enrollment penalty can be waived if I produce a government-issued document that confirms I returned on June 15th, 2016. I will appreciate if you suggest where I can get some document confirming that I arrived back in the USA on June 15, 2016.