Chemical pregnancy advice

Can anyone share their experience? I have been getting positive tests for 7 days now but the lines are all about the same color no lighter no darker.... I think I’m possibly 15-16 dpo not sure though as AF is not always the same. Just not sure bc my lines don’t seem to be getting darker and I would have thought they would have been darker by now. How long did your tests stay positive?? When did any bleeding start??