Enlarged Uterus?

[LeeAndra]

My sister and her DH are trying to have a baby. I'm not sure how long they have been trying (my sister and I are not close), but maybe a couple months. Anyway, she was supposed to start AF around Thanksgiving and did not. She took 3 pg tests over the course of a week, but all tested negative. She went to the doctor this past Tuesday, where she still tested negative, and the doctor said she has an enlarged uterus. She is scheduled for an u/s on the 21st to check for cysts. She said that she has never missed AF (like since she first started in middle school) before this past month.

I did some research online re: enlarged uteruses (uteri? *lol*), but wanted some RL experience from y'all. Do any of you have an enlarged uterus? What was the cause or causes? Were you able to successfully conceive despite having one?

[She is 26 years old and overweight with some IBS/lactose issues, but otherwise healthy. She does not have any biological children of her own.]

She is definitely a worst case scenario person and will make herself sick with worry until she has the u/s, so any advice or positive stories I could pass along to her would be great.