I had a very large one discovered during my 1st pregnancy. It's attached by a fairly slender 'stalk' to the outside of my uterus.
It grew massively during the pregnancy, and was really painful until 3rd trimester, but caused no other problems.
Had investigations after pregnancy and was advised not to get it removed until I was ready to accept that my family was complete, as the op carried a significant risk of needing an emergency hysterectomy. So I left it. Had heavy periods and some discomfort.
Pregnancy no2, and the fibroid continued growing, and hurting as it twisted on its stalk. But it probably outstripped its blood supply, because it stopped growing and stopped hurting - even shrank by the 3rd trimester.
Again, no problems from it, other than heavy periods after dc2.
3rd pregnancy, no problems at all. It did not grow or twist.
I started peri-menopause a couple of years after dc3 was born, and the fibroid started shrinking. I never bothered getting it removed, because it has not bothered me since.
The US scan shows its structure, and whether further investigations are necessary. It's more common to have fibroids after mid-30s than not, so they're virtually normal.
Because of the fibroid I was under consultant-led care for all my pregnancies. But all that meant was that some of my ante-natal appointments were with the consultant. Most of the time I saw midwives, and I had normal pregnancies and normal, midwife-supported births. One was even a waterbirth.
Hope my experience reassures you 