Bfps are not getting darker

I don't really know what to do.. I can't go to the doctors because of work :/ 
 I'm cd29, 13dpo and AF is due tomorrow.. I've been testing since 7dpo and since 8/9dpo I have been getting faint lines on all brands of tests.. I've tried as many different brands possible.. And all faint lines..
​Well, I'm 13dpo today, and was expecting yesterday's faint line on a casette test to get darker today, but I just tested with fmu and it's there but I don't think it's any darker.. Any suggestions as to what's going on?