So, did you leave the test sit or read it right away? Those tests will develop an evaporation line if they sit and you read it outside what the box says. Did the faint line appear immediately? If so, then you are likely pregnant as there is rarely a false negative with those. If you let it sit, you probably are not since you are on the pill BUT missing 2 to 3 days in a row was NOT good and could definitely mess up your pregnancy prevention.
So, let me know when you read the test, right away or did the line show later?