Should I get my hopes up or not.

I took a PT on 12 13 18 and today 19

12 & 13 blue test faint positive

18 1st response negative

19 88cent faint positive

Should I be worried that they haven't gotten darker by now or is it normal for the line to still be that faint.

I'm really irregular but my period should have came by now never gone this long with out one.