Pregnant?

I had unprotected sex on the 29th of June, I took plan B the next day. I’m waiting till Tuesday the 10th of July to buy a test because that’s my pay day so I’ll have money. According to this app I was supposed to get my period yesterday. However sometimes when I have sex (normally when it’s really close to my period, like the week before) my period moves. I don’t know if I should be worried. Cause I was really close to ovulation when i had sex and now I’m just scared.