Had unprotected sex thinking that my periods were done... dey came back during sex and I took morning after pills... my periods den went on for 4 more days and its wasn't a clean blood... and now this month was suppose 2 start my periods on d usual date the 17th or 18th it's the 21st but still nothing could I be pregnant?

You can always be pregnant if you have unprotected sex (even protected sex).
Morning after pills disrupt your cycle too.
There is just no way to know yet.
Please get on birth control pills instead of using morning after pills.