Just popping in from December EDD, because I've had similar large uterus measurements. It's interesting that your MW is already saying twins. It's pretty common for second/third/plus time moms to measure with a large uterus in the 1st trimester. It usually doesn't mean possible twins until the numbers are growing exponentially in the 2nd trimester. The uterus is just larger from bearing a child before.
Hope you get what you want of course! Just letting you know this is VERY VERY common with singletons of second plus pregnancies. I think it's also a bit concerning that your MW thinks you're having twins just based on this.
Wishing you all a happy and healthy pregnancy!
