Tests aren't working.

That's really tough for you. It's what they call a biochemical pregnancy. You did have some hCG, but not enough :-(

What my doctor always recommends is to get a blood test once the bleeding stops, just to make sure the hCG has gone back to 0. I don't want to scare you, but such a low hCG (and bleeding) can sometimes indicate a blighted ovum.
Unfortunately, I'm already a bit of a pro at this. I've had 3 biochemical pregnancies myself.
With one of them, despite the bleeding, my hCG kept rising very slowly. It was a blighted ovum that luckily resolved on its own after 4 weeks.

You just always have to be careful with things like this.

@amberle but what's the difference with a fertilized egg then? Sorry I'm totally out of my depth here luckily

@Elvira a blighted ovum is basically the same thing, just the term used in everyday language.
There is fertilization, but something goes wrong during cell division. So initially you do produce hCG, but it doesn't keep rising. Normally you'd get a spontaneous bleed and it's over, but the symptoms of a blighted ovum are very similar to those of a viable pregnancy. That's why it's important to follow up properly.

oh no @Elivira, I'm mistaken!!!!
If development stops very quickly, we call that a biochemical pregnancy, usually right after implantation or even before
If there is already development of a gestational sac, but no yolk sac forms, they call it a blighted ovum...

@amberle what a good explanation, thank you!