worried... chemical pregnancy?

I am worried... 10 DPO I tested positive and the line has been getting darker daily until this morning when it was lighter than yesterday's. It is still clearly a positive test...but I am worried this is the start of a chemical pregnancy. Any explanations? Both tests are from first morning urine so dilation isn't an issue. Period is due tomorrow so the timing is spot on if this is a start of a chemical. 😕
Pic below...top is yesterday AM and bottom is this AM