Faint line not getting darker

Hey ladies, so on 9 DPO I got a faint line! Over the last few days I’ve been testing with FMU and the line has not been getting any darker and I’m 13 DPO today. The line is still there just faint. I know it’s still kinda early but I’ve had 2 miscarriages over the last year so naturally I’m worried this is a chemical pregnancy. Has anyone else had this happen and had a successful pregnancy? Still have another 3 days till AF is supposed to arrive