O.k. Maybe somebody can help me. I had my period on 12/25/12. We had sex on 1/10/13 and here and there throughout jan. no birth control just pull out. Got my period on 1/20/13. Usually I have a regular  cycle of 28 days but this time it was 26 days. Now since my last cycle was only 26 days do I worry because its two days late now or do I need not to stress yet?