Emergency contraception

So I went and got the bc shot on Friday and Sunday I had unprotected sex with my bf and made a little mistake so I went to Walgreens and bought emergency contraception. It’s now Thursday and I’ve had cramps all week and my period is late by a day. Planned parenthood said it would take at least a week for the shot to start working. What if the ec messes things up? Am I just paranoid? I bought some test and idk when I should take them. Should I wait till I’m at least a week late? I have 3.