I'm on the pill but had missed a day and took it the next morning and my boyfriend and i used protection but my period is late. could i be pregnant?

Maybe. Maybe not.: 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 withdrawal 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 regular withdrawal period, then she is not pregnant.