uterus feels heavy?

Kaye • OB/L&D TECH. Second girl due in November. Hoping for a vbac
That's one way to explain my cramps. My uterus is sore. And feels heavy.  I'm only 11 weeks so that makes me nervous about how the rest of pregnancy will be. But when I'm sitting or laying it's fine. I hope it resolves. 
Anyone else ever felt this way?