How do you determine when you've missed your time?
Answers: It depends on what type of cycle you enjoy. For regular cycles, in which your spell comes around the same daylight (give or take 2-3) every month, it is from the first time of your last time of year. However, if you have an irregular time of year, it's harder to tell. Usually if you haven't have your period for nearly a month, you've missed it. Hope this helps!
P.S. I'm really a girl. I'm on my boyfriend's portrayal, haha. Sorry about that.
Unless you are regular and preserve track there really is no approach to know. Your menstrual period starts from the first time you bleed - so start counting then.