Stress can definitely delay your cycle! I am building a house and I got my period last week after 3 months!
But I got tested 2 times. Once after a week another time after 2mths and I was clear. A lot of things can change your cycle stress, diet, medication, alcohol, sleeping patterns….
The pill has about 2% of you still falling pregant so there is a tiny tiny tiny chance that the pill may not have worked. To stop all worries spare 30min of your time and get yourself checked out. At the end of it you could have been worrying all for nothing so if it does come a day or 2 late at least you wont be stressing in the mean time.
I have had moments where my period came a day or 2 late while on the pill from time to time. But go and get yourself checked out