My last period starting date is 6th of january. I had sex on 24th january. My underwear was worn at the time when ejaculation happened at the external vulva. My partner was naked. There was no penetration. But after ejaculation the semen touched my underwear. Also precum mostly dried touched my vulva. Can the semen pass through my underwear and make me pregnant. Today is 11th feb and I am not having period..