Pregnancy test staying light

I am about 5 weeks +2 days pregnant. I have had one miscarriage, and one healthy pregnancy. Because of my miscarriage I have been testing like a crazy person since I got my BFP last week. My test line is staying the same. Not getting any darker. Not really getting lighter, just not progressing. I have gotten positive digital as well. It’s definitely stronger the than first positive test though. I had some very very light dark brown spotting Saturday, the day period would have been due. Lasted about 24 hours and has since stopped completely. I am not cramping. I am scheduled for my first ultrasound on Dec 9th, but I am so nervous that the faint pregnancy test line is a bad sign. I called the doctors office, and office nurse told me everything sounds normal. I need to hear some positive stories!!! Anyone go through something similar, and have a healthy pregnancy??