Multiples or just a large singleton??

Saharh
So this is our fourth pregnancy.
I had my first U/S at 4 weeks, the tech and I saw three sacks in the uterus but when asked about them, the tech wouldn't provide details.. 
While checking out, the office admin said I was flagged as having triplets. 
My next U/S was at 10 weeks (happened to be a different tech), we saw one baby and one sack (no additional searching so I'm curious about the extra sacks...)  I was sent home and the tech told me to expect some bleeding, that "it was totally normal, just due to the extra sack".  
Now typically we are given a CD full of every image or video taking during the ultrasound (nearly hundreds of images) But with this ultrasound we were only given 2 images, close ups of our baby.  And I have not experienced any spotting or bleeding.
I have another U/S scheduled for this Friday, at 21 weeks.  
What are the chances I have/had multiples??  I honestly can't shake the thought of having my arms full, lots of crazy dreams and VERY random doodles from kids of "mommy with babies in her belly" so I'm hopeful. lol  
I can feel plenty of movement, strong kicking from many different angles.  It's usually easy for me to say "here's the baby's head, back, feet, etc" but I am SO confused with this pregnancy! I have no idea how one little lady can move this much.  All of my previous checkups have been quick, not that my OB is careless but I've done this so many times that there isn't much to go over.   Has anyone experienced anything similar?  I will definitely be asking for more details at my next checkup, but does anyone have any stories or explanations they would be willing to share?