Me And My Fiance Had Dry Sex... With Four Letters

Me and my fiance had dry sex... With four letters of clothing... I ejaculated in my pants the small wet dot was on my pant... We don't know it was in contact with her clothes or not... But then within 24 hours she took unwanted 72 pill... And 4 days before her periods date.. we tested the urine HCG test that was negative... What is the chances of pregnancy...? And can sperm go through clothes ?