I am confused about calendar method. Could you please help me. I am 20 yrs old. i forgot to record my january period... My recorded periods are feb. 7, march 7, april 10, may 7, june 7, july 6, august 11, september 9, september 28.. Well for october my fertility is october 7- 13?? Please correct me if im wrong. My question is, is it safe to have sex on october 16th, friday and onwards?? Kindly please answer my question. Thank you very much!