Please help me i am too frightened!

Me and my girlfriend both were wearing underwears only and  dry humping by placing my penis on her vagina and later there was an ejaculation too with both of ua wearing underwear so now i am worried about her pregnancy Previous history-She took unwanted 72 on 5th january so in january her periods were with less flow,her usual cycle is of 28 days But she got it in 26 days in month of february and now in march its her 29th day since first day of LMP still no period is there She had cramps and leg pain yesterday and the day before yesterday From today morning no leg pain and cramp ia there so in evening she took UPT which was negtive So can dry humping must have led to pregnancy???? And how much time should we wait for period and can she really be pregnant??