if she didn't have a period last month and her periods are irregular, why does she think she was supposed to get her period on the 16th?

since her periods are irregular you don't know when she's ovulating (unless she's temping and charting, which i doubt), and if you're having unprotected sex then she could very well be pregnant.

are you trying for a baby? if so, good luck. if not, she should get on the pill, that will help regulate her period and protect her against pregnancy.

has she tested since her period is late?

we never know when shes gonna have her periods...we're not exactly trying for a baby yet but we will be soon...she hasnt had a period in accouple months so idk if or when shes gonna ovulate..but since she missed her period again this month could she get pregnant anytime during the remainder of this month?

an yes she has been tested and shes not currently pregnant, she has very iregular periods as it is but i know she must ovulate at some point...i gues my ? is since she missed her period again this month is it possible to get her pregnant a week after she was supposed to start?

yes, because a woman ovulates *before* her period and since her period hasn't come and they're irregular you won't know when that will be.