I think im pregnant im 3 weeks late im cramping ?

Hmmm....: Can do a home pregnancy test (inexpensive and sold in stores everywhere). A urine test gives a reliable result 3 weeks after sex (3 weeks after when conception might have occurred), or about 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. Pregnancy is a common cause of a missed period, if having sex.