@Pep***
, Don't confuse your "admitted until" stamp that lets you stay in thailand (which is a year every time you enter the country for the validity of the visa) with when the visa expires.
IF you exit and re-enter the country on or just before March 9 2018 (the expiration date of the visa) you would get an "admitted until" stamp for another WHOLE year or March 2019 !!