Period a week after / Pregnant from precum over underwear?

the boyfriend and i were fooling around, and i rubbed his penis on top of his boxers. before i started, i noticed a little droplet of precum on the outside of the boxers. after i rubbed him a little bit (he never ejaculated) the precum was now in a little wet spot. then he put his jeans back on, and then he rubbed me on top of my underwear (never actually fingered me, or touched skin) my worry is that he touched some of the precum (maybe when he was putting on his jeans or something?) and then it was transferred to me when he rubbed me. could i be pregnant from precum? a week after the incident i got my period, though. does that mean i cant be pregnant? im only wondering because i heard that it sometimes takes 2 weeks to implant and have your body register the pregnancy and stop your period. im sure that it was a full period. if somehow i were pregnant, and then i got my whole period, would the fertilized egg have been flushed out? thank you so much in advance!!