Moms of multiples, help!

Ashley • I`m Ashley. My husband and I have been married for 6 years and together for 9. We have two beautiful girls and an angel.
So, I had a missed miscarriage in December at 10 weeks. We got pregnant our first ovulation cycle after that, which is unheard of for us!! Due 12/9. Because I'm high risk (loss and previous premature birth) I've been having my hCG checked since day 1. They seem really really high and I'm curious to how they are compared to the numbers of moms with multiples. I know numbers aren't a good indicator of much, but....you know. 
Here's the break down:
Ovulation was 3/17 (confirmed by opk)
HCG at 13 DPO 168
HCG at 15 DPO 580
Brown spotting: levels drawn immediately at 21 DPO 17,830!
17,830 at 4 weeks 6 days?!?!  
My numbers with my daughter were only 5,000 at 6 weeks with her! 
Thoughts? TIA!