Me and my girlfriend of 2 years had sex for the first time on Nov 23rd,it was protected (condom,but no birth control) and it did not break or anything and I pulled out just in case and all.Her period was to happen on Dec 1st(regular 28 day schedule) but it is now Dec 5th and it still hasn't happened.I have heard stress and hormones at this point can make it late be not all sure?And if it is stress,how long can stress delay your period?Please help,thanks.