I Had Unprotected Intercourse With My Partner On 15th Day

I had unprotected intercourse with my partner on 15th day of her cycle, her cycle is generally of 30-32 days. I did not ejaculate in her vagina by any chance. Within 30 hrs she popped an unwanted 72, today is the 13th day after we had sex and her next cycle is due after 3-4 days, she is 25 yrs old. Till now there is no abnormality as such related to her health, we did one home pregnancy test on 12th day after sex and it came out to be negative. Is there any possibility of pregnancy? Pleas reply soon