Different line strength for different tests??

Please tell me I have no reason to worry. I had a couple of different tests from trying so I don’t have the same strength on every one. I am 4 weeks today and I had 1 dollar store test left and it looks lighter than what I’ve been taking, but I’m worrying for nothing right?! Here is the progression for the 88 cent tests that I’ve been using. I’m 14dpo today. And then here is the dollar test.