A girlfriend(nt my boo) said she doesn't really know how to calculate safe periods so i decided to do a little research..
The following is the best & safe method to avoid pregnancy:-
First, one should know the duration of the cycle, i.e. first day of the last menstrual bleeding to the first day of the present menstrual bleeding. This is the duration of the menstrual cycle...
I hope say i dey on track..
You tried, but its always irregular!