Hello. very light pink spotting on day 19 of 28 day cycle with very light cramping. had sex on days 13,14 and 15. is this implantation?

A person can't tell: Wait. A positive pregnancy test can tell a woman that PRIOR spotting was actually implantation spotting. It can be hard to tell if a woman is pregnant because some of the symptoms seen in early pregnancy can also happen in non-pregnant women. A urine pregnancy test gives a reliable result about 3 weeks after sex (3 weeks after when conception might have occurred), or 1 week after an "odd" period.