Not to scare you but you’ve had unprotected sex on the day you’ve ovulated and have ended up with some semen on you. Yes you 100% could be pregnant. Semen can be present in pre ejaculate as well. I think you’ve also contradicted yourself saying you don’t get pregnant easily yet you’ve got 4 kids.
How long ago was this? Did you try a plan b that day? The positive ovulation strip makes the chance of pregnancy much higher (but not 100% of course)
@Claire all 4 were planned (took us months)
@Amanda 4 days ago :-/
Should be fine but you can always get a morning after pill from the chemist (within 48 hours of sex from memory)