Is there a reason to worry

I did a blowjob on my boyfriend and I was wearing only underwear and a very thin pad (the everyday ones).He cummed on my boobs while I was sitting in front of him and I felt the sperm started to go down to my belly and then to my underwear.I immediately panicked and got up to clean myself and as long as I saw the sperm was just right where my underwear started.Can I get pregnant that way?Like I know it’s stupid but can the sperm get all the way down to my vagina through my underwear and my pad while I was sitting?