Uterus measuring small?

Murphy
I'm a little worried... My doctor measured me two weeks ago and my uterus was 29cm. Today I measured 30cm. She said she thinks he's just in ball, but ordered an ultrasound later in the week just to confirm. I'm 34 weeks. I also haven't gained much weight even though I eat consistently. 
She kept saying "cord accidents" and I'm terrified something bad has or will happen which is why he's measuring so small...
Has anyone had anything happen like this?