Why aren't they getting darker ??? ?

Lovely • IG: Plentifully.day TTC #4. Sept 2014 tubal reversal. Feb 2016 HSG: blocked tubes. May 2016 IVF: failed. Aug 2016 BFP turned to 4th loss

Left to right dec 30, 29 and 28

I'm so scared of chemical

Has This happen to any of here, what were the results? Help