Actually, the morning after pill is a big dose of hormones that can throw your period off. It's common to be irregular after taking that. Do not have unprotected sex during this time because you never know when you'll ovulate again and you risk pregnancy. good luck
It maybe too early to tell. All you have to do right now is wait and do a test again 1 month after you have unsafe sex. If you still come out negative and still no period then time to visit your gynecologist as there maybe other reason for its absence.