Hello dear
I understand your concern
If sperm or precum come contact with the vaginal opening near to
vulva then it can cause
pregnancy.
But it also depend on the how much amount of sperm can enter in to the vagina.
Sperm near the vaginal opening can enter into the vagina and meet the ovum release during ovulation and fertilization will occur.
But if there is no precum and ejaculation then no chance of the pregnancy.
So there is some chance of the pregnancy.
If you do not want pregnancy,
You can take
I pill with in 72 hours of sex to prevent the pregnancy.
If 72 hours has been crossed then wait for the period to come.
IF period will delay by the 8-10 days then go for urine pregnancy test and or blood
HCG test to confirm the pregnancy.
If you will be pregnant then still you can terminate intrauterine pregnancy by the
abortion pill under the advise of gynecologist.