Delayed period after taking plan b pill but pregnancy test is negative?!

i took the plan b pill about 2 hours after unprotected sex a few weeks go n my period is due today n i never got it!. Its nEvEr late, it always comes exactly every 28 days, never irregular but the pregnancy test i took today came out negative, could i still be pregnant though!? I had sex again about a week after i took the pill but it was protected!. By how many days/weeks does the plan b delay your period!? can it even make u miss it for a month!? I've taken the plan b pill before last year and there were no problems with my period, it came on time, so this time I'm worried!. I know the sooner the pill is taken after unprotected sex, the more effective it is so mine should be extremely effective!? Thanks to anybody who answers my questions!.Www@Answer-Health@Com

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