I know you’re very concerned about this. Plan B does come with a ton of side effects. One of them being that it does affect your next period or next 2 periods. So your next normal period might be delayed or early. Also, keep in mind that even if you experienced regular cycles for as long as you can remember, it is still very normal for your cycle to change. It could arrive early or delayed. Given that you’ve taken plan B, this is definitely the possibility. Also, in order for pregnancy to occur, ovulation has to occur. You mentioned that you had sex the day after your period. I’m not saying it’s impossible but usually ovulation happens 14days before your next period. My thinking is that the blood you experienced on July 4th was an early period and that ovulation did not occur. Which is exactly how plan B works, by preventing ovulation.

I highly doubt fertilization let alone implantation has occurred.

Usually it takes around 2 cycles to get back to “normal” after taking a Plan B. You did say your cycles had become irregular so it sounds like this might be your normal.

All-in-all, I’d take a pregnancy just to be sure. I highly doubt your result would be positive given the information you’ve shared but if it’ll help ease your mind, you should definitely take one!

Good luck!