VVVFL on FRER for 5 days! Chemical? Help a girl out :(

I have had a very, VERY faint line on my FRERs for the past 5 days, 12-16 dpo. At 12dpo I had to tilt the test just right to see it, and at 16 dpo I can see it with no effort but it is still BARELY there (see pics). I had a chemical two months ago and had a faint line for a day that disappeared the next day and never came back. Never had such faintness for 5 days! So tell me....did anyone here experience this?? Is it a guaranteed chemical or has someone else been a super duper slow Hcg riser and had a healthy pregnancy? Thank you!

I should say, I bbt and my temp is still high. All tests have been FMU or SMU (still concentrated urine) and read between 3-5 min.