Help me out it’s late

My period is supposed to come today but still no sign of it, I have had sex only twice since my last period and it was always protected and condom never broke. But I can’t help to stress myself out did we do anything wrong? Could the period come late because I took plan b before my last period. My boyfriend says we are fine but I am felling very worried. Yesterday I had sore boobs but today I feel like I have cramps. Pls let me know I really need some help