Positive test after MC?

I know you can’t see it but there’s defo the very faintest line there. I had a MC on 30th August I was around 4 weeks but should have been 7 weeks. Since then I have had negative pregnancy tests. So I’m confused that I can see a line here. I know you can’t see it on the photos I’ve taken but take my word for it it’s there.

What could this be? They said to go back if I got a positive after 2 weeks obviously it’s only been around 10 days. But I have definitely got negatives before.

Also levels were 450 on sun 30th 250 on mon 31st (had to go to a&e so they checked again) and then 60 on wed 2nd so surely they’d be way way down by now, I stopped bleeding by 4th (Friday) obviously have had sex since then too. And also got BFN ever since.