Faint lines

For those who have had extremely faint lines, how long did it take for them to become more convincing?! This is now my 3rd consecutive morning of a very faint line (all pink dyes and 2 different brands involved) and thinking it's a possible chemical pregnancy. Has anyone had something similar and turned out to be ok? My previous 2 pregnancies ended in miscarriages at 8 and 6 weeks and wondering if my pregnancy hormones maybe don't get high enough to help baby develop. Any advice much appreciates, thanks!