So me and my bf had sex on 4/19, and my app says I was supposed to get it on 4/20. my periods have been regular ever since I've started it and the app is usually always right the only time it's off is if it comes a day later than It says and that only happened like three times. I bought a plan b on 4/20(the day after we had sex and he ejaculated) if I don't get it tonight, I will be 3 days late.. do you think the plan b threw it off ? I really doubt I could have get pregnant overnight - meaning the time I took to buy it.... and I'm having my regular period symptoms before it comes on so do you think I'm good?