Panicking..

I can't believe that i'm even posting this, but I need help....I am on yasmin, but take it continuously, either for two or three months. I think I have been on it for about 5 or six, and prior to that I was on regular yasmin. I have only had 1 or 2 periods on the new cycle, and I started immidiately--the first or second day of the placebo pills. It is now the third day and I haven't started my period yet...Is this normal? When I was on the regular yasmin cycle I often didn't start until the third or fourth day. I am terrified that I might be pregnant,...Any thoughts? I also know that stress can further delay a period so i'm sure worrying this much isn't helping anything. Any input would be much appreciated.