Period is 3 days late. had protected sex (condom) 4/5 & 4/18. now having cramps and light brownish spotting. one neg hpt, could i be pregnant?

Maybe not, but...: Can retest in 4-5 days. A urine pregnancy 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. If a woman gets her normal regular period, then she is not pregnant.