Since there was leakage of ejaculate from the condom and as you had unprotected cunnilingus there is a possibility of pregnancy
The earlier after the event, Plan B is taken, more effective it is. If taken after 72hours, it is about 50% effective.
Since you have taken Plan B in the second half of your menstrual cycle, it may delay your period by a week or so. So if your period is delayed by more than a week, get a pregnancy test done.
To avoid such unnecessary stress
I advise you to consult your doctor and start regular contraception like hormonal
contraception or have an intrauterine device
fitted as they are more effective than Postinor in preventing pregnancy.
It is wise to use barrier contraception
like Condom to protect yourself from sexually transmitted diseases.
I hope I have answered to your satisfaction. If you have any further queries do contact me through healthcare magic