If you miss 1 or 2 days of taking your pill, there is a chance, albeit small, to get pregnant. You didnt specify when you had missed your pill in relation to when you had unprotected sex. If it was within a couple of days, chances are small, but you could become pregnant. If had unprotected sex several days(4 or 5) after missing a dosage(but immediately resumed normal dosing), you should be okay.
Above all else, an HPT would be definitive.