according what you told the possibilities could be,
will delay periods sometimes by affecting hypothalamic-pituitary axis.
2. normally also duration of menstrual cycle can fluctuate between 21 to 35 days. So you may get periods shortly.
can be present in pre-ejaculate
fluid which may lead to pregnancy
Now you once do urine pregnancy test,
if test is negative, consult gynecologist and take tablets for withdrawal bleeding.
if positive, you and your partner decide what to do next according to your planning.