I had unprotected sex on the same day I was expecting my periods. I also took an I pill the very next day but I still haven't got my periods yet even though it has been 5 days since then...
My periods are not very regular also...
Is it possible that I'm pregnant...
Please help me out asap...

Yes, it is possible you are pregnant.

The I Pill can stop you from having a period for one or two months.

Also the I PIll is not 100 percent effective, so pregnancy is of course possible.

You will have to wait and see if you get your period next month

So until when should I take a pregnancy test to confirm that I am pregnant or not?

I think when your next period is due, would be a good starting point (because enough time should have elapsed to detect if you are), with another a week after that for two more weeks if the result is negative.. Any earlier and you are unlikely to get a reliable result.