Usually on a 28,29,30 day cycle. varies every month. this month my period was from 10th-14th. unprotected sex on the 26th. how likely is pregnancy ?

Highly likely: With your cycle length you would be ovulating about cycle day 14-15-16. By having sex on cycle day 12, as you describe, your chance for conceiving would be in the 10 to 15% range..

Possible: This timing would have definitely put you in the most fertile part of your cycle so pregnancy is a possibility. If you don't want to be pregnant you need to begin a reliable method of contraception and if your period is late you need to check a pregnancy test. You are still in the time where emergency contraception is an option but the efficacy decreases as the time from intercourse increases.