Spotting very light pink 3 weeks before period is due could i be pregnant?

Maybe but bit early: Spotting can be secondary to implantation meaning a pregnancy can be trying to "stick" to the uterus but this usually occurs one week before the period should come. It can indicate abnormalities in female hormones or thyroid or prolactin (hormone to produce breast milk) or abnormalities in the uterus like polyps or fibroids or even cervical inflammation or irritation. Do a pregnancy test if late.