Missed Period!!!!

I’ve been on Mirvala 28 since June of 2017 and normally after I come off the pill I get my period either the day after or always at the latest 3 days after coming off of it. But in January I was a little sloppy with the consistency of taking it (for some reason there was no days tracker in the box to help me and I have terrible memory so if I don’t have that I’ll forget to take it). So I missed a day had some spotting, started taking it again, missed it again and had more spotting, then took another pill, and then when I missed it the third time I just decided to stay off and wait for my period. Now it’s been since January 16th and I’ve seen no signs of my period, so I took two tests and they’ve come back negative. Do you think it could just be stress or because I was so forgetful with my pills that I’m having a delayed period?? Thanks xx