Next question,
What is this reader compatiable with?
You are in Thailand correct?
I found a lot of Mifare Classic readers there.
So the FlexM1 SHOULD work.
Since we know it reads MN, deoending on what you have it emulating, it SHOULD also work with NTAG.
Therefore, I have 2 suggestions for you.
1st, and probably best option.
A FlexNT in my opinion is probably the best flex:size performance implant you can get.
2nd option.
You will need to ask @amal or @tac0s if they still have the original copper antenna FlexM1’s
Amal pulled them from the store for fear of failures, however I have had mine for over 6 years and zero issues.
IF they are willing to sell you one, you mighy just need to agree to a no warranty and accept that it may fail.
Mine is in position P1, and it is very good for presenting to readers.
Good luck