Missed Miscarriage

So I found out the horrible news last week that I'm having a missed miscarriage. I was 7 weeks but my gestational sac was empty and measuring at 6 weeks. I still hung on to every little bit of hope and prayed that my next scan would show a baby. I went for my second ultrasound yesterday and had an empty sac measuring at 6 weeks and 2 days. My hcg levels were at 12,000 last week and are now at 10,000. The doctor is continuing measuring my levels. I think the hardest part is waiting for it to happen. I'm devastated but I just want to move on with my life. Has anyone had this happen? How long did it take to pass it naturally and how long did it take to get pregnant again?