What Does Delayed Periods Post Unprotected Sex Suggest?

hai doctor,my girl friend has last periods on feb 27 2015,nd after that we both have done sex,but with cndomns only,but second time sex i insert one time to her vagina before putting condomn,only one time,that i didnt feel of sperm coming or i dont have any reaction at that time,but now tz 29th day..periods yet not came,what to do