[Always *]

I've had my period come anywhere between 5 days and 3 weeks late during periods of stress (mental stress, bodily stress etc). The fact of the matter is that if you're sick (or under/overweight, starving, etc.) it can cause irregularities to your period, I'd give it a while longer, 2 days isn't significant even at the best of times. if your still worried despite the fact that we've all reassured you and it still hasn't come then go get a test just to be certain.