I ended my period 3 days ago but i'm getting cramps , abnomial pain , sore nipples, and headaches. is it possible to be pregnant?

Unlikely, but...: Can do a home pregnancy test if no period comes next month. A urine test, done correctly, gives a reliable result 3 weeks after sex (3 weeks after when conception might have occurred), or 1 week after missing a period. If done sooner, a positive result is likely real, but a negative result may be due to testing too soon, and thus lead to a repeat test.