prolonged miscarriage:(

We found out we were pregnant only a week and a half ago with our first baby. Last Thursday we had our first OB appointment. We were able to see a healthy little sac with a yolk sac and measured at exactly 5 weeks. Doc said everything looked perfect! The very next night out of nowhere I started to bleed. Not terrible, not enough to fill up a pad, but bright red blood when I went to the bathroom. We went to the emergency room and they did labs and a transvaginal ultrasound. My HCG came back at 8490, and the transvaginal US showed an irregular gestational sac with a yolk sac. I've been a mess all weekend. I've had no cramps, all my symptoms are still here. But I've continued to bleed. Today we saw our OB and he confirmed the irregularity of the gestational sac and there was no yolk sac that he could see :(. He said there's a 99% chance that I am miscarrying. Unfortunately my body has started to develop the placental sac and isn't wanting to let go. I feel like this is torture. Doctor told us we could miscarry at anytime this week and it could even prolong into the following week. Merry Christmas to us :(. Trying to keep a level head. I know this is definitely a miscarriage I just don't understand why it won't just happen. Emotional torture :( hoping to have my rainbow baby someday. I don't know how I would ever be able to go through this again. I never realized how much I wanted to be a Mother until I got pregnant. I feel so responsible for not doing everything by the book. I know they say it's not your fault and it just wasn't meant to be, but I can't help but feel like this is my fault.