should it be darker?

Ashley • Angel baby 3.27.16🖤 Rainbow 1.6.17💖 Due with #2 oct.18

Hi y'all! So I've been testing the last week (AF was due yestersay) I got very faint positives on FRER and on blue line wa lmart brand early result for the last few 3 days. the FRER seemed to get a tad darker but still a squinter. This morning I took an 88 cent cheapie from Wal-Mart and it was so so faint! way more faint than the FRER and blue dyes... how reliable are those 88cent as far as line progression? I'm worried my line should be darker on all the tests (I've had 3 miscarriages and a chemical) so I'm a nervous wreck. Thanks!