Lately i been feeling to vomit but i don't, i also had no period yet but they are irregular ones? thanks for answering

Pregnancy worries?: A urine pregnancy test, done correctly, gives a reliable result about 3 weeks after sex (3 weeks after when conception might have occurred). 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. A woman can do a urine preg. test from time to time, if she is worried about pregnancy. Urine tests are sold everywhere.