Is this cause for worry?

The top test is 16 dpo, middle is 17 dpo, and the bottom is 18 dpo. Im super nervous about this pregnancy as I lost my baby at 17 weeks a few months ago. Is line progression any indicator of a chemical pregnancy? Are the tests too light? Should I be worried? My OB office doesn't give appointments before 8 weeks and that's the time they order blood work. Just looking for some thoughts. I could just be overthinking it but ever since the loss of my baby at 17 weeks, I've been cautious about getting excited. Thanks in advance.