Uterus measuring big?? Help

I'm a fraternal twin and my husband and I are 7w5d along with our second pregnancy.. I ovulated 10 days late (CD 23-24) so I thought I would only measure 5w3d.. But she took a feel then got her midwife to take a feel and say we are closer to 9w5d... I'm worried because we had a late term loss in July with our son.. And I don't want anything to happen to this baby... Could it be twins? A hematoma? Just a lot of fluid? Just a big uterus? Thoughts??