So, first. To clear this up, peeing in no way prevents pregnancy. :>) That's so surprising to me that they'd make such a comment in a class as it is false. Pulling out also does not prevent pregnancy. Any time you put a penis in your vagina when you are not fully up to speed on the pill or he's wearing a condom, you've risked pregnancy.
I'm not even sure how to advise you though. At this point, you have a lot of hormones floating around in your system. I don't think you got pregnant but absolutely YES, your hormonal system will be a hot mess. The plan B wasn't a great idea. I always took my pill 'sometime' within a 24 hour period and didn't worry about exactly the specific time of day. If you skip a pill, you can take two the next day and you are probably covered as long as it is a one time thing. But were you JUST on it for 7 days as in this was your first month taking it?
If not, then yes. you'd always be covered at any time during the month no matter the day. But you just started to take it and missed a pill? Is that what you are saying?
Anyway, again. Don't think you got pregnant but think you will have a holy heck of a messed up cycle now for another 2 months. I like that you are responsible and not wanting to get pregnant though . . . it's just kind of the hard way to go about it.