[Always *]

I must say that I agree. There really is not reason to not test even though the chances are low. Your contraception was compromised, yes, but it wasn't rendered totally ineffective and that combined with the PCOS probably makes it less likely but the chance is still there. You could always buy some tests either at a drug store or at a dollar store and take at least 1, though 2 or 3 is recommended, and make sure that you aren't pregnant (or are). If nothing else at least you are ruling out the options of why you missed your period.

You could also consider that you have a cyst preventing you from having your period. The whole point of taking the pill when you have PCOS is to prevent you from getting more cysts correct? So if the pill was compromised due to the antibiotic it's quite possible that it compromised its ability to prevent a cyst as well as preventing pregnancy. Especially given that you experienced menstrual symptoms but no period. So if you rule out pregnancy it might be worth speaking to your doctor about having a cyst. I am not sure what the protocol is for you, but depending what your doctor expects she/he may want to do an ultrasound and monitor the cyst if there is one to make sure it disappears.

Otherwise, it might just be from having had the flu and the stress from Christmas. But I think that those are 2 possibilities worth ruling out.