Extremely low hcg…

I am supposed to be 10 weeks. I had some light spotting after a yeast infection which I didn’t really think anything of and then I started bleeding but still wasn’t heavy but I did start to cramp at that time. I had my blood drawn and my hcg levels were SOO low. So I’m thinking that I miscarried around 4-5 weeks {which I found out at 3 weeks and 6 days according to my last period) but didn’t show any signs of miscarriage until I started bleeding at 10 weeks. I am devastated. I don’t know why my body failed me… why I had a sticky baby but it just stopped growing and my body kept it this long.