Ok, I'm probably just freaking out about birth control but...?

I'm on the patch, and I have been since May 9. There's no chance of STDs so don't answer about that because I'm in one relationship and it's serious and we've been tested. I started it that date, the Sunday after I started my period. I misread and we had unprotected in the first week and I took Plan B onestep since it said the patch wasn't effective until a week after starting. We had unprotected sex the other day and I'm due for my period this coming week and I've been on that patch for a full month now. Do I have a high chance of getting pregnant? Or will the patch more than likely have prevented it? I'm worried that I won't get my period due to the Plan B (and new patch on Sunday) but then how can I really know?