Chemical possibly?

I tested wih a frer on Friday 3/20 and got a very faint positive, yesterday 3/21 tested again and the Line hadnt gotten any darker still super super faint. I tested this morning 3/22 and the line is barely noticeable. I also took a digital today and it said no- (negative). I think I could have been around 9 dpo on 3/20. I go in for blood work tomorrow to see what's going on. From all my findings I'm assuming I'm having a chemical. Anyone have any similar stories and end up being pregnant or was it chemical after all?