When I had my dd at age 28 (it was an unplanned, but not an emergency c-section), the doctor rather offhandedly remarked that I had "some" fibroids, and that the largest one was about the size of a golf ball. He said they were nothing to be particularly concerned about, and that most women have them. My mom (who was right there as he told me this) concurred, and I knew that she had a hysterectomy at the age of 40 in part because of fibroids, but only after having three children.
When I had ds in 2000, my doctors had trouble doing amniocentesis because, as the technician said, there were fibroids "everywhere". When ds was born, my OB/GYN said that the largest fibroid was the size of a softball.
But it wasn't until 2004 that I ended up having a hysterectomy, at which time I had "more than 30" fibroids (I guess they stopped counting?) and none of them were over 3.5 cm. in size.
Moral of the story: While sometimes fibroids interfere with fertility or the ability to bear children, it's not a foregone conclusion by any stretch of the imagination. I wasn't even a high-risk pregnancy with either of my kids.
Also, the size of the fibroid doesn't matter nearly so much in terms of discomfort or symptoms as its location or type... i.e., a fibroid deep in the uterine wall might cause more trouble than one that's hanging by a stalk, but it's all very individual.
You're in the right place to find plenty of information about what you may or may not be facing along the road. Welcome to you.