Coitus interruptus, is a less efficient method to prevent pregnancy with a average failure rate between 20-25 per 100 women years as compared to combined oral contraceptive pills with failure rate of less than 1 per 100 women with ideal use.
I would suggest that you use an emergency post coital contraceptive agent containing Ullipristal acetate, Ella One ( even if 72 hours) have passed, as it acts upto 120 hours. And reduces pregnancy rate to 9-18 per 100 women years.
Levonorgestrel containing emergency contraceptives, like I pill reduce in efficacy after 72 hours, especially after 96 hours. Other alternative would be a copper T IUCD, inserted within 5 days.
Ella One is contraindicated and
liver disease, so it would be wise to rule out pregnancy from event prior to use.
Please consult yr local Gynaecologist regarding the same. And note the date of the next menstrual cycle.
Do let me know if there are any other queries.
Regards,
Aditi