Help!

Hi, i'm trying not to get pregnant. my period is very very irregular. it can sometimes comes on the first day of next month. and no later than that. So this is how it goes. base on my first period was on 22nd( As in really first period when i was 13) and its always irregular. so recently, my period is late for 6days. And i had unprotected sex with my husband on the 27th. And even until now 1st of feb, my period has yet to come.. is that possible to get pregnant?