Faint lines for days

Lovely • IG: Plentifully.day TTC #4. Sept 2014 tubal reversal. Feb 2016 HSG: blocked tubes. May 2016 IVF: failed. Aug 2016 BFP turned to 4th loss

I've been getting faint lines since Thursday(26) but they don't seem to get darker, has this happened to any one and got a bfp? Af was due Christmas day

It's nerve wracking. I don't have a doc visit until the jan 8th since she's on vacay