I didn't find any information so:

I have 12 month validity, multi entry non-immigrant visa..

I would like to stay more in Thailand so is it possible to continue my visa somehow?

I didn't find any information so:

I have 12 month validity, multi entry non-immigrant visa..

I would like to stay more in Thailand so is it possible to continue my visa somehow?

How old are you? Are you married to a Thai lady? Have you Thai kids?

Do you have a Thai wife and 40k per month family income?

Are you over age 50 and have a pension of 65k per month?

Are you a student?

Do you work here with a work permit?

If you have no valid/approved reason for extension of stay it is not possible. Nor is it likely that any Consulate in the area would issue a new visa of that type.

How old are you? Are you married to a Thai lady? Have you Thai kids?

I dont have any approved reasons for extension but I heard that just for going border it's possible to get 3 moths more and after that 2 or 3 months more, so totally can stay 1 year and 5 or 6 months?

You have to go to the border one or two days before the visa expires. You get 3 more months and can stay with this visa 15 months.

Correct on the 15 months, but do not forget to check the "permitted to stay until ..... date"

for a border - run every 90 days or so.