havea non-immigrant,category, M entry,expiring 9/2018.  on 10/15 was going to take a family trip to bali, come back to bkk on 10/27 and then go to honoi until 11/6.expats informed me that i needed a reentry stamp.today i went to nong khai immigration and was informed by senior officer that i didn't need one and could have as many entries and departures up to 9/18. where am i, could someone kindly give me advise.thank you.

If you have a multiple entry non immigrant visa you can do unlimited entries up to the enter before date on it.

No need for a re-entry permit until after the visa expires to keep the last entry from it valid if you want to travel.

thank you very much