How long will a plan B mess up my period?

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Took a plan B 3 months ago. Had a 12 day cycle week i took it, 24 day cycle, 31 day cycle, now it’s day 32 of my cycle and no period. My cycles are usually short and i don’t think I’m pregnant (no intercourse but extremely slim chance from oral? maybe he came near my vagina???) but this is unusual. any help?