I do know your disappointment - I had two blighted ova - one at 7 weeks and one at 11 weeks - so I know that sadness. I lost two pregnancies, like you lost one baby in this pregnancy
in the early stages is VERY VERY complicated, and the one twin didn't attach properly or didn't have a viable placenta, or didn't have healthy DNA.
Don't let this ruin your joy for the life you're carrying, embrace13. Your body tried to hang on to both babies, but wasn't able to.