I'm sorry that you are having this uncertainty during the holidays.
You're situation sounds similar to what happened to me, and that did end in miscarriage at 11w. If you've only had one sonogram, the dr. will probably order another in 7 days. If you want to be sure schedule it for 10. For me, the view ever week wasn't helpful becuase the fetus was growing, just not a week's worth in a week. More like 6 days worth in a week. It wasn't until I waited 10 days for there to be a definite major discrepancy.
When my pregnancy was done, I told my son (then 4), simply that I had been mistaken. I thought I was going to have a baby, but I'm not. Sometimes we get it wrong. He was okay with that.
While the miscarriage was devistating to me, it did help me decide that I did want to add to my family. Four months later I was pregnant again, was a nervous wreck, but delivered to term. My miralce is now 6 and I couldn't imagine not having her. If I hadn't of had the miscarriage, I would have a 7y, but I wouldn't have my exact little girl, and she is awesome!
Sending hugs for peaceful answers.