Hi ,I Generally Have Periods On The 7th Of Every

Hi ,I generally have periods on the 7th of every month, last month we had unprotected sex during my periods. In order to avoid pregnancy I took ipill on the 4thday of my periods. Now this month it's 19th today and I have still not started with my period. I hav taken a home pregnancy test too and it's negative. Pls guide, I dono wat to do?
In the meanwhile I would also like to tell you that from last 1 month I'm trying to reduce weight so I have been working out for almost 2 hours in gym and controlling on diet. Earlier I was doing very good but off late I feel fatigued in workout, could it be because of the above reasons? Pls guide, I'm getting stressed.