Thanks for the query.
As you had unprotected intercourse
around the time of ovulation there is possibility for pregnancy
But just by symptoms we cannot come to one conclusion.
The spotting you had could be implantation
bleeding or it could be scanty menstrual flow.
Scanty menstrual flow can occur due to many causes like anemia, hormonal
imbalance, thyroid abnormalities etc.
So by doing confirmatory test only, we can come to one conclusion regarding pregnancy.
As your periods are already 8 days delayed, better to go for urine pregnancy test now.
If the test comes positive, it is good and you can continue the pregnancy.
If the test comes negative, consult gynecologist once and get evaluated to find out the cause for scanty menstruation