I guess I am not understanding your true question . . . you had unprotected sex, used Plan B, THEN got your period (late, but you got it), since then have only had protected sex, and now your 2nd period after Plan B is late (I am leaving out all the flu shot/sick, since it seems somewhat irrelevant here).
Do you think that somehow you are still pregnant? We can't answer that, only a doctor can. Do you think that somehow since the Plan B delayed your Oct period, it may or may not be responsible for the delay of your Nov period? Again, we can't answer that, only a doctor can (or nurse line might be able to help).
Kudos for being responsible (mostly) but honestly only your doctor/clinic can answer these questions - even then they are subjective to other outside factors like stress or eating habits or a million other things. Make an appointment, have them double check you aren't pregnant (which is probably your real concern here) and then likely once you know you are not, you will lower your stress and get your period.
Good luck!