I missed my period yesterday. I took a pregnancy test this past Friday, 2 days before the missed period, vvfl. I've continued taking tests daily,

still faint lines..it doesn't seem to be getting noticeably darker..I haven't gotten AF yet. I'm not sure what to think. Has anyone else had a similar experience? I've tested in the morning too. I took one of the clear blue digital and it came back as pregnant. I also took another first response test, still a noticeable faint line. Since it's not getting significantly darker, could this be a miscarriage? I've never had one.