Lighter pregnancy tests

Found out 3 days ago that we are expecting baby #2. The day before finding out I had some bleeding, just when I wiped and not all day. Then last night some more spotting, it was light pink that turned brown. Has anyone experienced this and went on to have a good pregnancy? With my first I spotted brown for about one day around 6weeks pregnant. I’ve heard that if you continue to take tests every few days the line on your test should get darker as your hcg doubles but mine don’t look like they are getting darker… hoping to get into my doctor in the next few days. Does it matter that my test line is not that dark or looks fainter than yesterday?

First picture is from yesterday and second is from this morning. I’m 19 dpo today.