I just experienced my first miscarriage and boy it’s confusing!

I got my faint positive on the 8th of January. It never got darker and I started bleeding the 10th. Went in to my ob and got hcg test done. It was 8. They wanted me to come back the 21st to test again.

The 19th I wondered if my tests were negative by now so I took one and man it was a BFP for suuure. I was having symptoms and everything. Went back the 21st for my 2nd hcg test and it was 87! I didn’t find out until this morning though😔 and last night I started bleeding again and my tests are now negative. And my ultrasound this morning showed nothing

When exactly did I miscarry?