Please help: How can I tell if it's breakthrough bleeding or a period?

I had to skip a birth control pill thursday when prepping for a colonoscopy (i have crohns disease, had to get a checkup). Then I went back to taking regular pill fri & sat nite.. My period is due this coming tuesday, tomorrow (the 20th). Well since yesterday (saturday), I have been bleeding a fair amount especially when i pee & have some cramping.. I'm uming my period came early because of skipping a pill? I'm just wondering because I had "breakthru bleeding" once when I had messed around with my pills to delay a period for a vacation. You know, it wasn't an actual period, but sure looked like it! But i know that was different cirstances..So I want to be sure it's my real period lol.. Last nite i had a sugar pill, btw..I take Kariva 28-day pack. At end of each pack it has 2 sugar & 5 lower-dose pills. Any tips/advice on this appreciated! Especially those with experience in this!