Line not getting darker. HCG delayed

I tested positive on 12/19 (13 dpo) and performed a test every AM since then. I am worried that the pink line is not getting much darker relatively. I normally wouldn’t worry but I had some spotting on 12/19 and 12/20. My HCG test result which was supposed to come on 12/20 is delayed till after Christmas and my OB wasn’t very reassuring.

Should I think anything of it? Is there anything I can do to help with the pregnancy hormone?

Please share your knowledge. This is my first pregnancy.

Photo from 18 dpo