Apri bc pill

I started taking Apri about 4-5 months ago. Every month my period is not aligned with the packet and this month my period didn’t come. It is over two weeks late but i have had cramps for a few days. I have been sexually active however we always use conforms because I like to be as safe as possible. I have taken 4 test ranging from the day of the missed period till today. All were 100% negative. Should I be concerned and make an appointment with my doctor?