Afraid I'm going to lose the pregnancy, are dollar tree tests accurate?

I've been having positive tests since last Saturday when I started testing with the frer 6 days sooner tests. I then did the clear blue and they also got positives, and then I bought Dollar tree tests after I went to the doctor for a test and they told me it was negative. My Dollar tree test have been showing faint lines but I'm now 3 days past my missed period and am estimated to be about 4 weeks 5 days and the Dollar tree tests are not getting any darker and now I'm extremely worried. I know that you can't test progression with tests, but I was expecting it to at least get dark enough to be noticeable after this amount of time 😭 It's pretty much stayed the same last 3 to 4 days and now I'm worried that could be chemical. Has anyone else had anything like this with the Dollar tree tests and it turn out ok?