4 weeks today

Hello. I know that I am still very early. I have had a few chemical pregnancies. I had tested at 3 weeks 5 days and there was what I would say not faint but not dark line. The blue tests are always light for me so I stick with FRER. I took a test each day since. I had a very dark test two days ago and then a faint one this morning. I took another an hour later and there was a dark second line. My question is has anyone every had this happen? Did you have tests from the same box read differently? I also take my vitamins before bed and my pee is always fluorescent in the morning, could this have made the test a little faint? I am so excited but I am also a nervous reck that I will have another chemical pregnancy. This is the first time I have had two dark lines. I wish everyone here the best of luck on your journey.