Not sure what to do

Okay so I’m on the patch(birth control) and my third week ended last Friday so I’m suppose to have my period now. Well I had sex last Wednesday (we used a condom) and when I got home I jumped in the shower and the patch was coming off so I replaced it right when I got out. Well my period hasn’t came yet but I have back pains and cramps here and there but nothing yet. Is this normal? And what if it doesn’t come by Friday do I start my patches again or wait? Please help me be put at ease 😭