Could Delayed Periods Be Due To Intake Of I Pill?

I took an ipill on 19th of December 2014 within 2 hours of unprotected sex, the last time I had my menses was on 2nd December 2014. I have had no withdrawal bleeding after taking the ipill and my periods are delayed for 10 days now. I took a home pregnancy test which came out to be conusing because there is a faint second line but nothing could be seen on the vaginal ultra sound. is the delay of periods due to ipill or am I pregnant?