AF 4 days late and faint lines aren't getting darker

I was due for AF 4 days ago, I'm 17dpo and had a faint line on a frer at 15dpo with fmu. I've been testing since but with a different brand of test as I'm saving my frer until tomorrow morning to tests with fmu. Lines are still there, or so I can see but they definitely aren't getting any darker since 14dpo. They are so light they almost look like they aren't even there but the only reason I say they are there is because my boyfriend and my mum are both very skeptical about faint lines and usually can't see anything when I can, and they both have agreed that they can see my faint lines. I'm nervous because I feel like they aren't getting darker and by 17dpo they should be darker by now. I just don't really understand what is going on and my doctor won't test me until I'm a week late so I'm having to sit tight. He suggested that I wait a week because apparently sometimes a positive doesn't show until a week after AF is due but after seeing so many women get strong lines by 14dpo I'm anxious. I haven't posted this in success stories as I feel that it's not a success, not yet anyway. I'm still testing and the lines just aren't getting darker.. Does anyone have any idea why? Should I just sit back and hope AF will come? I haven't been late in months and I understand that stress can make AF delay but I have purposely tried to not think to much about the tests so if AF is going to come she can. I'm just very nervous and unsure how to feel. Does anyone think it could be a ectopic? I have heard that thy real ease hcg very slowly and I'm unsure as to what to do about that. I mean, I don't even know if I am pregnant but I posted my frer in the faint lines thread and everyone said thy could see just very very very faint.. I just don't know what to do and I've come here mainly for advise.