Doctor I Had Sex With My Boyfriend On 11th Day

doctor i had sex with my boyfriend on 11th day after my periods started and we used condom and still he ejaculated outside and neither he was able to fully insert his penis in me and then i got brownish and someday red spotting after 9 days of that thing happened but just for 3 to 4 days and now my peiods are due from 3 days although i have my periods always after or on my due date. so can i get pregnent and if yes then what natural remedies can i use right now to avoid this