3 weeks 4 days miscarriage?

On 8/15 I started to bleed a bright red around time period would have been due my pregnancy was confirmed by beta at 12pm 8/15 it was at a 45. I continued to bleed kind of like a period on 8/16 I passed this at 7pm I redone blood work on 8/17 at 12pm it was at a 85 my doctor said it was almost a perfect double so she didn't think I was miscarrying. My lines on tests have continued to get darker and they are even darker today. My bleeding stopped last night I've had a couple of spots today maybe 2 times when I first woke up around 7 but haven't seen anything since around 1030 this morning. Has this happened to anyone else? I'm so confused I just knew I had miscarried but my beta still doubled.