HCG question

Is it normal for the levels of HCG in your urine to go down toward the end of the day? For the past two days my PM tests have been faded. I’m testing so much because this is my first pregnancy after loss and it helps my anxiety to see those lines stay dark. But last night we both had a total meltdown when we saw them lighten significantly. I go in tomorrow for my second blood test, but I’m terrified after watching the lines fade twice now.