Uterus measuring bigger..

Jess • I wear lots of hats.
Today I'm 7w5d and I had my first appointment... Doctor said that she feels my uterus more along the size of 9w5d... I temped and looked to confirm ovulationso I'm perplexed on why I would be measuring this big... Could it be a hematoma? Twins? I'm a fraternal twins so I guess it's possible... A lot of amniotic fluid? My ultrasound is on the 16th... I'll be 9 weeks exactly... Ideas? Has this happened to you?