First signal

Does anyone have any experience with the first signal taking forever to turn positive and remain light?

I am sure I am pregnant. However it took a lot of time and money and prayer and fertility treatments to get pregnant with my son. We decided 2 months ago to start trying for baby #2. We wanted to try on our own for the next few months and start fertility treatment if necessary at the beginning of next year. Thankfully my body must have reset after having my son. I started getting sick after dinner every night around 8dpo. I took a first signal and it was negative. I continued to be nauseous for the next 5 days. I caved and took another first signal and it appeared negative. I went to work like normal and got home super late that night. I had thrown the test in a drawer. I opened that drawer after just telling my husband there was no way I wasn’t pregnant (I was super sick my first pregnancy the entire time, lost 20 pounds and threw up the entire 40 weeks, I was feeling the same). The test was OBVIOUSLY POSITIVE. I was worried because it was way past the time to read it so I took a clear blue that came with a opk kit and it was also positive. I took it at 9pm. In the morning I took a FRER and it had the lightest line ever. If I hadn’t gotten two positives before I would have dismissed it as negative. I was worried that wasn’t turning and was talking to a friend about it. We had always heard pink dye were more accurate. She convinced me to take a digital at lunch and it came back pregnant. I have continued to take the first signal because I can’t get in for lab work until next week and they continue to be positive but aren’t getting much darker and still take quite a while to turn positive. I was getting worried so I took another digital yesterday and still positive. Has anyone had weird experiences with the first signal test not getting darker? I know I am over analyzing but I haven’t been sick in two days and my boobs are tender but not nearly as tender as I remember with my son.