Period log

Is there any way for me to log in my period dates from 2012-2013? I missed to record other periods and I can't seem to find a pattern. I am not on any birth control and I'm not yet sexually active (saving myself for when I'm ready and hopefully my wedding day)  My periods are on different days last anywhere from 1 day to 14 days. Start anywhere from a week to four weeks apart. Need some help!