5 week concerns...

LP
Got my second BFP last week after a mmc in September. We are soooo happy but in the last two days I've started to get quite worried that the subsequent tests (dollar store) I've been taking haven't darkened much!! I took another CB digital and it's still saying 1-2 weeks. :( Has anyone gone through this test comparison hell? I feel like I should have never tested after the first one or two! I'm currently 20dpo and AF was due a week and one day ago.