if you've ever dated more than 3 or 4 women in your entire life then you would know some women can go as long as 7 or 8 weeks without having her period, and then after that she can be on her next rag as soon as 3 weeks later. not everyone's body works exactly the same all the time, and people like you are proof that i need to stop assuming that everyone knows shit as basic as this.
Canada