Should I be worried?

If I had unprotected sex on the first day of my period and took the morning after pill about 48 hours later , should i be worried about being pregnant? 
It's been about two weeks (the incident happened on 30th Aug and its 10th Sept today). And especially today, I felt like vomiting when I was on the bus. Rarely happens. Also, according to the calendar, it's my ovulation week.
So could it be symptoms of ovulation? Am I being overly worried? How does one know if the morning after pill works? 
Would really appreciate it if someone replied me. Thank you!