I think you are not on a OA visa but a yearly extension for being retired. and your last visa was a non immigrant 'O' visa, which has long expired, if that is the case you do not need insurance,
as you are out of Thailand you should have a re-entry permit issued by immigration, if so you should be stamped in until March, if you do not have a re-entry permit, then you will have to start the process over again. and entry on a visa exempt entry which at the moment is a 60 days permission to stay stamp.