I had sex on the 26 of april and took the emergency contraceptive i then had a short three day(30-2may) period light brown bleeding last period before that's was the 13-18 april i've had now period since. could i be pregnant?

Maybe not, but...: Plan B or other emergency contraceptive pills work most of the time, but not all of the time. One should do a home urine pregnancy test 3 weeks after Plan B, to confirm non-pregnancy. Also, use reliable forms of birth control so that Plan B or other emergency contraceptive pills will rarely be needed (hopefully never) in the future.