Would you please help??? please share ur experience

I'm 3 weeks 2 days post d&c. I've been testing with pg test to see if hcg is leaving. Test on top is from Monday. The bottom is from last nights. Why would the latter be darker? Is this normal? Did yours do this? I thought the more days that go by the less potent the residual hcg would be. Of course I've had sexual activity within this time period but I don't think it's a new pregnancy.